Roman Military Stone-built Granaries in Britain 9780904531459, 9781407319674

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Roman Military Stone-built Granaries in Britain

Anne P. Gentry

British Archaeological Reports 3 2

1976

British Archaeological Reports 122

Banbury Road. Oxford OX2 78P, England GEKERAL EDITORS

A.R. Hands, B.Sc., M.A., D.Phil. D.R. Walker, M.A.

A. C .C. Brod r bb, M.A. Mrs. Y.M. Hands

ADVISORY EDITORS �eil Cosso!1S, M.A., F.S.A., F.M.A. C.B. B..;;:-g��s, ,\LA. ProfessorB.W. Cunliffe, :'-.1.A., Ph.D .. F.S.A. Santa Chadµick Hawkes. B.A.. :'11.A.. F.S.A. Professor G.D.B ..Jones, M.A.. f).Phil.. F.S.A. P.A. \lellars, M.A., Ph.D. Frances Lynd:. :\1.,.\ .. F.S.A. P.A. Rahtz, :\LA.. f.S.A.

B.A.R. 32, 1976: "Roman Military Stone-Built Granaries in Britain" © Anne P. Gentry, 1976

The author’s moral rights under the 1988 UK Copyright, Designs and Patents Act are hereby expressly asserted. All rights reserved. No part of this work may be copied, reproduced, stored, sold, distributed, scanned, saved in any form of digital format or transmitted in any form digitally, without the written permission of the Publisher. ISBN 9780904531459 paperback ISBN 9781407319674 e-book DOI https://doi.org/10.30861/9780904531459 A catalogue record for this book is available from the British Library This book is available at www.barpublishing.com

RO MAN MI UTARY STONE-BUILT GRANARIES IN BR ITA IN

CONTENTS Page Acknowledgements List of Figures List of Plates, Tables and Maps Abbreviations Bibliography PART!

1. 2. 3. 4. 5. 6. 7. 8.

Introduction Principles and Problems of Grain Storage Classical references to Grain Storage Comparison of excavated structures Structural aspects, and their interpretation Provisioning of Roman Forts and the Capacity of Granaries Appendices Index

1 2 5 7 15 23 35 47

PA.RT II

Catalogue of excavated examples

49

1 . Introduction 2. Location of sites discussed 3. Comparison of external wall and buttress dimensions 4. Catalogue

51 52 55 57

ACKNO WLEDGE ME NTS Th is work i s b ased u pon a n u ndergradua te t hes is s ub m it ted t o t he Un ivers ity o f Wa les i n 1 975. Iam g rea t ly i ndebted t o Dr. M. G . J arret t f or h is a dv ice a nd e ncouragemen t.

He h as v ery k ind ly p rov ided d eta ils o f g arr isons a nd r elated i nscr ip t ions

f or e ach c a ta logue e n try a nd h as a lso r ead a nd c r i t ic ised a n e ar l ier d raf t o f t he t ex t. Is hould l ike t o t hank Mr . G . Boon o f t he D epar tmen t o f Archaeo logy . Na t iona l Museu m o f Wa les , f or h is h elp a nd f or mak ing p rov is ion f or me t o e xa m ine a nd we igh a s e lect ion o f r oof ing t i les f ro m Caer leon.

A lso , Dr.

W. H . Mann ing w ith who m Ih ave d iscussed s evera l p o in ts. Mr. W. R . Dav ies o f t he Depar t men t o f C iv il Eng ineer ing , U .W .I.S . T . a nd my f ather Mr . P . W. H . G en try g ave v a luable a ss is tance i n t he p reparat ion o f t he s ect ion u pon s tructura l r equ ire men ts.

I n t h is c onnect ion Iam a lso

e x tre mely g ra tefu l t o Mr. J a mes S i mpson f or h is c ons iderab le h e lp i n c o mp i l ing t h is d a ta a nd f or c heck ing t he c a lcu la t ions i n t he a ppend ices. Iam g ratefu l f or t he h elp g iven b y Mr. R . W. H owe o f t he Pes t I nfestat ion Con tro l Laboratory , w ith who m Ih ave c o m mun ica ted o n an u mber o f p o in ts. Mr. T . Co mp ton u nder took t he p ho tograph ic r educt ion o f my p lans.

A lso

Mr. A . E . J ohnson d rew t he p oss ib le g ranary r econstruct ion a nd t ha t o f t he t i led r oof a nd a lso c ontr ibu ted much a dv ice a nd c ons truct ive c r it ic is m. Iam a lso i ndebted t o Mr . J . P . G il la m who h as v ery g enerous ly a l lowed me a ccess t o ma ter ia l o n t he g ranar ies a t Corbr idge i n a dvance o f h is own p ub l ica t ion , a nd t o Dr. D . J . Breeze f or p rov id ing i n for ma t ion o n h is r ecen t e xcavat ions a t Bearsden. F ina l ly I s hou ld l ike t o t hank P ro fessor G . D . B . J ones f or h is h e lpfu l c o m men ts o n t he o r ig ina l t ex t.

L IST OF F IGURES Page 1 .

S uggested r econs truct ion

2 .

T i led r oof :

3 .

S ou th S h ields :

4 .

Gra in d istr ibut ion model

5 .

Granary f loor a rea a s ap ercen tage o f f or t a rea

6 .

Granary p lans :

1 7

s ugges ted c onstruct ion S everan S upp ly Base

Granary p lans :

2 9 3 1

Amb les ide, Ba l mu ildy , Bar H il l , Benwel l , B irrens

7 .

1 9 2 1

6 1

Brecon Gaer , Brough o n Noe, Cadder , Caerhun , Caernar fon , Caersws I

6 5

S .

Granary p lans :

Ca melon , Cappuck , Caste l l Co l len , Cas t lecary , Cas t ledykes , Chesterle-S treet , Chester ( 3 )

6 9

9 .

Granary p lans :

Corbr idge.

7 3

1 0.

Granary p lans :

Chesters , Cra mond , Craw ford I , Croy H il l ,

S tructural Phases

Dru mburgh , Gel l igaer H 1 1.

Granary p lans :

7 9

Greatchesters , Ha ltwh ist le Burn , Hardknot t , H igh Rochester , Housesteads, I lk ley

8 3 8 7

1 2.

Granary p lans :

Lyne, Mu m r i lls , Newstead

1 3.

Granary p lans :

O ld Church , Bra mpton , O ld K ilpatr ick ,

1 4.

Granary p lans :

Rough Cast le, S lack , S outh S h ie lds,

P enydarren , R ibchester , Rudchester T e mp leborough

9 1 9 3

LIST OF PLATES IA B

Corbridge: west granary Corbridge (west). Longitudinal sleeper walls supporting flagged floor

IIA B

Corbridge (east). Corbridge (east). and drain

IIIA B

Ventilator \Yith central mullion Loading platform. portico column,

Housesteads (north). Pillar floor supports Housesteads (north). Relationship of ventilator to floor supports

TABLES 1. 2. 3. 4.

Granary floor area expressed as a proportion of the total internal fort area Comparison of granary floor area, presumed garrison and theoretical annual grain requirement Comparison of fort area, granary floor area and garrison requirements relating to timber granaries Dimensions of external walls and buttresses

30

32 34

55

MAPS 1. 2.

The location of granaries studied Northern Britain

53

54

ABBRE V IA T IONS

AA, 1 -4

Archaeo log ia Ae l iana , i st t o 4 th s er ies. S oc iety o f An t iquar ies o f Newcast le u pon Tyne.

An t. J .

T he Ant iquar ies J ourna l , L ondon.

Arch . Ca mb.

Archaeo log ia Ca mbrens is , Card if f .

Arch . J .

Archaeo log ica l J ourna l , L ondon.

AW

Archaeo logy i n Wa les , Card if f .

BAR

Br it ish Archaeo log ica l Repor ts , Ox ford.

BBCS

Bu llet in o f t he Board o f Ce lt ic S tud ies , Card if f.

Br it .

Br itann ia , L ondon .

Bu ll. En t. Res.

Bu l let in o f En ty mo log ica l Research .

Car m. An t iq.

T he Car mar then An t iquary , Car mar then.

C IL

Corpus I nscr ip t ionu m L a t inaru m.

Curr . Arch.

Curren t Archaeo logy .

C W, 1 -2

Transact ions o f t he Cu mber land a nd Westmor land An t iquar ian a nd Archaeo log ica l S oc iety , Car l is le.

Derb. Arch. J .

Derbysh ire Archaeolog ica l J ourna l.

Dur. Un iv. Gaz.

Durha m Un ivers ity Gazet te.

J . Agr ic. Eng. Res.

J ourna l o f Agr icu ltura l Eng ineer ing a nd Research.

J . Chester. Arch. S oc.

J ourna l o f t he Arch itectura l , Archaeo log ica l a nd H istor ic S oc iety

. . .

o f Chester .

T RS

J ourna l o f Ro man S tud ies , L ondon .

Kent Arch. Rev.

Ken t Archaeo log ica l Rev iew.

Mon t. C ol l.

Co l lect ions We lshpoo l

New Phy t.

New Phy to log ist .

PPS

Proceed ings o f t he Preh istor ic S oc iety .

PSAS

Proceed ings o f t he S oc iety o f An t iquar ies o f

.. .

p er ta in ing t o Montgo merysh ire,

S co t land , Ed inburgh. R IB

Co l l ingwood , R . G . a nd Wr igh t , R . P . T he Ro man I nscr ip t ions o f Br ita in , 1 . Ox ford 1 965.

S aa l. J . TBGAS

S aa lburg J ahrbuch , Ber l in. T ransact ions o f t he Br isto l a nd G louces tersh ire Archaeolog ica l S oc ie ty.

Trans. B ir m. Arch. S oc.

T ransact ions o f t he B ir m ingha m Archaeo log ica l S oc iety .

VCH

V ictor ia H istory o f t he Coun t ies o f Eng land.

YAJ

Yorksh ire Archaeo log ica l J ournal

B IB U OGRAPHY

C lass ica l References Marcus Porc ius Ca to

De Agr icu ltura

C icero

I n Verr .

Colu me l la

De Re Rust ica

He r od ian P l iny

Na tura l is H istor ia

Polyb ius

The H istor ies

SHA

S cr ip tore s H is to r iae Augu s tae Had r ianu s

Tac itus

Agr icola

Marcus Teren t ius Varro

Res Rust icae

V itruv ius

De Arch itectura

B ibl iography f or g ranar ies B irley , E , 1 938 :

Excava t ions a t B irrens , 1 936-7, PSAS LXX I I ( 1937-8 ), 2 80.

B irley , E , 1 960 :

Ches ters Ro man F or t , M in istry o f Works Gu ide ( 1960 ).

Bosanquet , R . C ., 1 904 : ( 1904 ), 2 35. Breeze , D .

J.,

1 968 :

Excavat ions a t Housesteads Ro man For t , AA2 XXV ,

Excavat ions a t S outh S h ields 1 966 a nd 1 967,

Archaeo log ica l Newsbu i iet in No. 5 0 ( Apr il 1 968 ). Brew is , J . Parker , 1 924 :

Ro man Rudches ter .

Repor t o n Excava t ions , 1 924 ,

AA4 1(1925 ), 9 9. Bruce , J . Co l l ingwood , 1 857 :

Excavat ions a t Bre men iu m AA 2 1 , ( 1857 ), 7 6.

Bruce , J . Co i l ingwood , 1 860 :

Excava t ions a t B irdoswa ld AA 2 I V , ( 1860 ),

2 49. Buchanan , M., 1 900 :

An a ccoun t o f t he Excavat ion o f t he Ro man s tat ion o f

Ca melon , n ear Fa lk irk , S t ir i ingsh ire , PSAS XXXV , ( 1900 ) , 3 65. Buchanan , M., 1 903 : PSAS =

Excava t ion o f Cast iecary f or t o n t he An ton ine Va l iu m ,

V I I, ( 1903 ), 3 08.

Buchanan , M., 1 905 :

Repor t o n t he S oc iety 's e xcavat ion o f Rough Cast le o n

t he An ton ine Va l iu m , PSAS XXX IX , ( 1905 ), 4 74.

Buckland, P.C. and Dolby, M. J., 1972: 274.

Doncaster, Curr. Arch.(1971-2),

Buckland, P.C. and Dolby, M. J., 1973:

note in Brit. IV, (1973), 282.

Charlesworth, D., 1963: (1963), 148-152.

The Granaries at HardknottCastle, CW 2, LXIII

Christison, D., 1895: An account of the Excavation of Birrens. a Roman station in Annandale, PSAS XXX, (1 95-6), 112. Christison, D., 1901: Excavation of the Roman Camp at Lyne, Peebleshire, PSAS XXXV, (1901), 180. Clarke, J., 1933:

The Roman Fort at Cadder, Glasgow, 1933.

Collingwood, R. G., 1915: The Exploration of the Roman Fort at Ambleside, cw 2, xv(1915), 24. Collingwood, R. G., 192 : HardknotCastle, CW2, XXVIII(1928), 329. Collingwood, R. G., 1933: Bruce, J. C. Handbook to the Roman Wall, 9th ed. byCollingwood, Newcastle upon Tyne, 1933. Curle, J .• 1911: Newstead: A Roman Frontier Post and its People, Glasgow, 19 11, 58. Daniels, C. M., Jones, G. D. B. and Putnam, W. G., 1966: (1965-6), 112-5. Daniels et al., 1967:

MontColl. 59

Mont Coll. 60 (1966-7).

Dodd, P. W. and Woodward, A. M., 1923: Excavations at Slack, 1913-15, Y.A.J., 26(1920-3), 21. Evelyn-White, H. G., 1914: Excavations at Castell Collen, Llandridnod Wells, Arch.Camb. 69 (= Arch.Camb. 6.14, 1914), 19. Forster, R. H. and Knowles, W. H., 1909: Corstopitum: Report on the excavations, AA 3 V, (1909), 314. Forster, R. H. and Knowles, W. H., 1910: Corstopitum: Report on the e cava ions, �3 VI, (1910), 209-13. Forster, R. H., 1912: Corstopitum, a brief report on the Excavations from 1906-1911. 1912. Forster, R. H. and Knowles, W. H., 1915: Corstopitum: Report on the excavations, AA 3 XII(1915), 227. Frere, S. S. and St. Joseph, J. K. S., 1974: Longthorpe, Brit. V, (1974), 1-38. Gibson, J. P., 1903: (1903), 33.

The Roman Fortress at

Excavations atAesica, GreatChesters, AA 2XXIV,

Gibson, J. P. and Simpson, F. G., 1909: Excavations at Haltwhistle Burn, AA 3 V, (1909), 250. Gillam, J. P., 1961a: Excavations at Haltonchesters, Dur. Univ. Gaz., (1961), 6. Gillam, J. P., 1961b:

note inJRS 51, (1961), 164.

Gillam, J. P., 1962: note in JRS 52, (1962), 164. Gillam, J. P., 1967: note inJRS 57, (1967), 177-8. Gillam, J. P. and Tait, J. 1968: The Roman Fort at Chester-le-Street, AA 4 XLVI, (1968), 75-96. Gillam, J. P. and Tait, J., 1971: The Investigation of the Commander's House Area, on Site XI, Corbridge, 1958-70; The Structures, AA 4 XLIX, (1971), 1-28. Hartley, B. R., 1958: note inJRS 48, (1958), 135. Hartley, B. R., 1966: Proc. Leeds Philosophical and Literary Soc., xii, (1966), 23-72. Hartley, K. F., 1972: note in Brit. II, (1972), 254. Haverfield, F., 1899: Excavations at Drumburgh ,CW 1 XVI, (1899), 81. H.M.S.O., 1967: RCHM(Scotland), Peeblesshire I. H.M.S.O. 1967, 172-5. Robley, B., 1969 & 1972: Neronian-Vespasianic Military site at The Lunt, Baginton, Warwicks., Trans. Birm. Arch. Soc. 83, (1969), 65-129 and 85, (1972), 8-92. Hogg, A. H. A., 1968: Pen Llystyn: A Roman Fort and Other Remains, Arch.J. 125, (1968), 101-93. Hopkinson, J. , 1928: The Roman Fort at Ribchester, 3rd edition by Atkinson, D., Manchester, 1928, 14. James, F. T., 1906: Roman remains: Penydarren Park, Merthyr Tydfil, Arch. Camb. 61, (= Arch. Camb. 6, 1906), 193-208. Jarrett, M. G., 1968a: The Roman Fort at Brecon Gaer: some problems, BBCS 22, (1966-8), 426-32. Jones, G. D. B. and Birley, A. R., 1966: note in JRS LVI, (1966), 196. Jones, G. D. B. and Wild, J. P., 1967-9: Manchester University Exc�vations at Brough on Noe, Derb. Arch.J. LXXXVII and LXXXIX(1967-9). Jones, G. D. B. et al., 1972: note in AW(1972), 23-4. Jones, G. D. B. et al., 1973: note in Brit. IV, (1973), 272. Jones, G. D. B. and Little, J. H., 1973: Excavations on the Roman Fort at Pumpsaint, Carmarthenshire: Interim Report 1972. Carm. Antiq. (1973), 3-21. Macdonald, G., 1906: Roman Forts on the Bar Hill, Glasgow, 1906, 40. Macdonald, G. and Curle, A., 1928: The Roman Fort at Mumrills, near Falkirk, PSAS LXIII, (1928), 431. Macdonald, G., 1937: A further note on the Roman Fort at Croy Hill, -PSAS LXXI, (1936-7), 56. Manning, W.H., 1974: Excavations in the Roman Fortress at Usk, Monmouth­ shire, Roman Frontier Studies 1969. ed. Birley, E., Dobson, B. and Jarrett, M. G., (1974), 61-9.

Maxwell, G .. 1972: Excavations at the Roman fort of Crawford, Lanarkshire, PSAS 104, (1971-2), 147-200. May, R., 1922: The RomanForts of Templeborough near Rotherham, Rotherham, 1922, 39. Miller, S. N., 1922:

RomanFort atBalmuildy, Glasgow, 1922, 26.

Miller, S. N., 1928: RomanFort at Old Kilpatrick, Glasgow, 1928, 21. Ministry of Works, 1952:

Guide to the RomanFort at Housesteads, ed.Birley,

E., 1952.

Norman, H., 1859:

Excavations atBirdoswald, AA 2 IV, (1859), 249.

Petch, D. F. and Thompson, F. H., 1959: Excavations in Commonhall St., Chester, 1954-6: The Granaries of the LegionaryFortress of Deva, Chester Arch. Soc. J. XLVI, (1959), 33-60. Philp, B., 1971: The ClassisBritannica and Saxon ShoreForts at Dover an interim report, Kent Arch. Rev. 23 (1971). Philp, B., 1972:

The Dover RomanForts, Kent Arch. Rev. 28 (1972).

Pryce, F. N., 1940:

Mont. Coll. 46 (1940), 67 ff.

Rae, A., 1959-62: notes in JRS 49 (1959), 104; JRS 51 (1961), 161; and JR S 52 (1962), 163. Rae, A. and v., 1974:

The RomanFort at Cramond, Brit. V, (1974), 165.

Reynolds, P. K. Bailie, 1938: Excavations on the site of the Roman fort of Kanovium at Caerhun, Caernarvonshire, Cardiff, 1938. Richmond, I. A., 1934:

The RomanFort at South Shields, AA 4 XI (1934), 92.

Richmond, I.A. and McIntyre, J., 1939: The AgricolanFort atFendoch, PSAS LXXIII, (1938-9), 110-154. i hmond, I. A. , 1940:

The Romans in Redesdale, NCH XV, (1940), 63 ff.

1941:

note in JRS 31, (1941), 129.

1947:

note in JRS 37, (1947), 165.

1948:

note in JRS 38, (1948), 82.

1950:

Newstead, PSAS LXXXIV, (1949-50), 19.

Richmond, I.A. and Gillam, J. P., 1950: Excavations on the Roman Site at Corbridge, 1946-9 AA 4 XXVIII, (1950), 152-201. Richmond, I. A., 1959: note in JRS 49, (1959), 106-7. 1961:

Robertson, A. S., 1964: London, 1964.

note in JRS 51, (1961), 158. The RomanFort at Castledykes, Edinburgh and

Robertson, A. S., 1975: Birrens (Blatobulgium), Edinburgh, 1975. Robertson, A. S., Scott, M. and Keppie, L., 1975: Bar Hill: A RomanFort and itsFinds, BAR 16 (1975).

S haw , N ., Sm ith , D . J . a nd G il la m . J . P ., 1 958 : S hef f ie ld Un ivers ity , 1 959 :

n ote i n JRS 48, ( 1958 ).

n o te i n JRS 4 9, ( 1959 ), 1 08.

S i mpson , F . G . a nd R ichmond , I . A ., 1 931:

Excava t ions o n Hadr ian 's Wa l l

i n t he B irdoswa ld-P ike H il l S ector , 1 930 , C W 2 XXX I, ( 1931), 1 22-34. S i mpson , F . G . a nd R ichmond , I . A ., 1 936 :

The Ro man For t o n t he S tane-

g ate , a nd o ther r e ma ins , a t O ld Church , Bra mpton , C W 2 XXXV I, ( 1936 ), 1 74. S i mpson , F . G . a nd R ichmond , I . A ., 1 941:

The Ro man For t o n Hadr ian 's

Wa l l a t Benwe ll , AA 4 M X , ( 1941), 1 7. S i mpson , F . G . a nd R ich mond , I . A ., 1 952 :

The Ro man For t a t Dru mburgh ,

CW 2 L I I , ( 1952 ), 9 . S tevenson , G . H . a nd M i l ler , S . N ., 1 912 :

Report o n t he Excava t ions a t t he

Ro man For t o f Cappuck , Roxburghsh ire , PSAS XLV I ( 1912 ), 4 58. S t. J oseph , J . K . S ., 1 951:

A ir r econna issance o f Nor thern Br ita in , JRS 4I,

( 1951), 5 2-65. S t. J oseph , J . K . S ., 1 961:

A ir r econna issance i n Br ita in 1 958-60, f RS 5 1,

( 1961), 1 24. Wade , W. V ., 1 952 : Ward , J ., 1 903 :

n o te i n JRS 42, ( 1952 ), 9 1.

The Ro man For t o f G el lygaer , L ondon , 1 903.

922 : Whee ler , R . E . M., 1 LXXV I I,

The S egon t iu m Excavat ions , 1 922, Arch. Ca mb.

( = Arch. Ca mb. 7 , 2 .1922 ), 3 02.

924 : Wheeler , R . E . M., 1

S egon t iu m a nd t he Ro man o ccupat ion o f Wa les , 1 924.

926 a : Whee ler , R . E . M., 1

Excavat ions a t Brecon Gaer , Y Cy m mrodor ,

1926 ). XXXV I I, ( Whee ler , R . E . M., 1 926 b : Woodward , A . M., 1 926 :

Ro man For t n ear Brecon , 1 926.

The Ro man F or t a t I lk ley , Y . A.J. 2 8 ( 1924-6 ), 1 84.

Genera l Ar ms trong , M. T . a nd H owe, R . W., 1 963 :

The s aw-toothed Gra in Beet le

Oryzaeph ilus s ur ina mens is , i n h o me g ro wn g ra in , J . Agr ic. Eng. Res. 8 No. 3 , ( 1963 ), 2 56-261. B ir ley , E ., 1 953 :

Ro man Br ita in a nd t he Ro man Ar my , Kenda l , 1 953.

B ir ley , E ., 1 961:

Research o n Hadr ian 's Wa l l , Kenda l , 1 961.

Boon , G ., 1 974 :

S i lchester , 1 974.

Boo th , L . G . a nd Reece , P . 0 ., 1 967 : Brass ing ton , M., 1 975 :

The S tructura l Use o f T i mber , 1 967.

A Reappra isa l o f t he Western Enc lave a nd Env irons ,

Corstop itu m , Br it. V I, ( 1975 ), 6 2-75. Breeze , D . a nd Dobson , B ., 1 969 : ( 1969 ), 1 5.

For t t ypes o n Hadr ian 's Wa l l , AA 4 XLV I I,

Breeze, D. and Dobson, B., 1973: The Development of the Mural Frontier in Britain from Hadrian to Caracalla, PSAS 102, (1969-70), 109-21. Breeze, D. and Dobson, B., 1974: Fort Types as a Guide to Garrisons: a Reconsideration, Roman Frontier Studies 1969, (1974) , ed. Birley, E., Dobson, B. and Jarrett, M. G. Bulmer, W., 1969: The Provisioning of Roman Forts: ration storage, AA 4 XLVII. (1969).

A reappraisal of

Bulmer, W., 1972: Review of Rickman's Roman Granaries and Store­ buildings, JRS 62, (1972), 205-6. Collingwood, R. G. and Richmond, I. A., 1971: Britain, revised 1971.

The Archaeologyof Roman

Coombs, C. W. and Freeman, J. A., 1955: The insect fauna of an Empty Granary, Bull, Ent. Res. 46, (1955), 399-417. Coope, G. R. and Osborne, P. J., 1967: Report on the Coleopterous Fauna of the Roman well at Barnsley Park, Gloucestershire, TB GAS 86, (1967). Crawford, 0. G. S., 1949: Topography of Roman Scotland North of the Antonine Wall, 1949. Davey, N., 1961: A History of Building Materials, London, 1961. Davies, R. W., 1971:

The Roman Military Diet, Brit. II, (1971).

Fink, R. 0., 1971: Roman Military Records on Papyrus, 1971. Frere, S. S., 1967: Britannia, 1967. Fryer, J., 1973: The harbour installations of Roman Britain, Marine Archaeology, (Colston Papers), ed. Blackman, D. J., 1973. Haverfield, F., 1916: Modius Claytonensis: from Carvoran, AA 3 XIII, (1916). Haverfield, F. and Collingwood, R. G., 1920: Forts, CW 2 XX, (1920). Helbaek, H., 1952:

the Roman Bronze Measure The Provisioning of Roman

Early crops in Southern England, PPS 18, (1952), 194.

Helbaek, H., 1964: The Isca Grain, a Roman plant introduction in Britain, New Phyt. 63, (1964), 158. ....._ Hinton, H. E. and Corbet, A. S., 1972: Common Insect Pests of Stored Food Products, British Museum (Natural History), 1972. H.M. S.O., 1966: Farm Grain Drying and Storage, Ministry of Ag. Fish and Food, Bulletin No. 149, 1966. H.M.S.O., 1971:

Farm Buildings, Ministry of Ag. Fish and Food, 1971.

Holt, J. and Nix, J. S., 1961: 9-5-61.

Safe in store, Farmer and Stockbreeder,

Jacobi, H. von, 1914: Rtlmische Getreidemtihlen, Saal. J. III, (1912), 7595.

J arre t t , M. G ., 1 968 :

L eg io XX Va ler ia V ictr ix i n Br ita in , Arch . Ca mb. 1 17,

( 1968), 7 7-91. J asny , N ., 1 944 :

Whea t Pr ices a nd M il l ing Costs i n C lass ica l Ro me , Whea t

S tud ies o f t he Food Research I nst itu te, Vo l. XX No. 4 , (March 1 944 ), S tanford Un ivers i ty , Ca l iforn ia , 1 37-170. Macdona ld , G ., 1 934 :

T he Ro man Wa l l i n S co t land , 2 nd e d it ion , 1 934.

Mann ing , W. H ., 1 975 :

Ro man M il itary T i mber Granar ies i n Br ita in ,

S aa l. J . XXX I I, ( 1975 ), 1 05-129. McKay , W. B ., 1 971:

B u ild ing Cons truct ion , Ia nd I , 1 971.

Mil ler , S . N . ( ed.) 1 952 :

The Ro man Occupa t ion o f s ou th-west S cot land ,

G lasgow , 1 952. Mon te , G . d a l 1 956 :

L a p resenza d i i nset t i d e i g ranar i i n f ru men to n eg l i

s car i d i e rco lano , Red ia , 4 1, ( 1956 ), 2 3-8. Mor itz, L . A ., 1 958 :

G ra in Mil ls a nd F lour i n C lass ica l An t iqu ity , Ox ford ,

1 958. Mor ley , A ., 1 953 :

S treng th o f Mater ia ls, 1 953.

Nash- W i ll ia ms , V . E ., 1 959 :

The Ro man Fron t ier i n Wa les, Card if f , 1 969

2 nd r ev ised e d it ion b y M ichael G . J arret t. N ix , J . 5 ., 1 956 :

Dry ing a nd s tor ing g ra in o n t he f ar m , Un ivers ity o f

Ca mbr idge , Farm Econo m ics Branch Repor t , 4 4 , 1 956. O 'Ne i l l , H ., 1 965 :

S tone f or Bu ild ing , 1 965.

Osborne, P . J ., 1 971:

An i nsect f auna f ro m t he Ro man s i te a t A lcester ,

Warw icksh ire, Br it. I , ( 1971), 1 56-165. Ox ley , T . A ., 1 948 :

T he S c ien t if ic Pr inc ip les o f Gra in S torage , L iverpoo l ,

1 948. Petr ikov its , H . v on :

D ie I nnenbauten r im ischer L eg ions lager wahrend d er

Pr inz ipatsze it , 1 974. R ich , A ., 1 901:

A D ict ionary o f Ro man a nd Greek An t iqu it ies, 1 901.

R ickman , G . E ., 1 971 :

Ro man Granar ies a nd S torebu ild ings, Ca mbr idge,

1 971. S inger , C . e t a l., 1 956 : S i mpson , G ., 1 964 : Sm ith , W., 1 849 :

AH istory o f T echno logy , I , Ox ford , 1 956.

Br itons a nd t he Ro man Army , L ondon , 1 964.

D ict ionary o f Greek a nd Ro man An t iqu it ies , 1 849.

S o lo mon , M. E . a nd Ada mson , B . E ., 1 955 :

The p owers o f s urv iva l o f s torage

a nd d o mest ic p es ts u nder w in ter c ond it ions i n Br ita in , Bu l l. En t. Res. 4 6, ( 1955 ), 3 11-355. Tho mpson , F . H ., 1 965 : Ward , J ., 1 911 :

Ro man Chesh ire , Chester , 1 965.

Ro mano-Br it ish Bu ild ings a nd Ear thworks , London.

Watson . G . R ., 1 969 : Webs ter , G ., 1 969 :

The Ro man S o l dier , 1 969. The Ro man Imper ia l Ar my , L ondon , 1 969.

Wel ler , J . B ., 1 965 :

Far m Bu ild ings , I , L ondon , 1 965.

Wilkes, J .

Ear ly Four th-century r ebu ild ing i n Hadr ian 's Wa ll For ts ,

J.,

1 965 :

f ro m Br ita in a nd Ro me, e d. J arrett . M. G . a nd Dobson . B ., 1 965.

INTRODUCTIO N The identification and location of the granaries (horrea) within Roman forts has seldom presented any real problems to their excavators. In the past, the tendency has been to cut sections through the defences of a recognised Roman fort, locate the gateways, and to concentrate attention upon the central build­ ings. The principia always occupied the centre of the fort, fronting onto the main thoroughfare (via principalis), and the granaries were almost invariably situated on one or both sides of it, within the central range. From the beginning of the 2 nd century A.D. forts began to be rebuilt or constructed de nova in stone. The most likely candidates for masonry cons­ truction were these central buildings, and even in forts where the timber barracks were never replaced in stone the principia and horrea were frequently stone-built and substantial. The distinctive ground plan of these buildings; the courtyard plan of the principia and the thick walled, heavily buttressed granary make them easily recognisable. It is for these reasons that so many granaries have been uncovered by nineteenth and early twentieth century excavators. Nevertheless they still present problems to the modern archaeologist. A large proportion of the granaries included in this study were excavated more than half a century ago, at a time before the introduction of many modern techniques, when often the principal method of excavation was to locate one wall and simply follow it round to produce a plan. The interior may have been examined completely, or may have been subjected to the digging of a diagonal trench across the building in the hope of detecting any internal features. Many details con­ cerning the construction of individual granaries have thus been inadequately recorded. In addition, from the excavation reports it is often difficult to pin­ point a date for the granary because the main preoccupation was usually with the periods of occupation of the fort as an entity rather than charting the his­ tory of individual structures within. It is the purpose of this study to carrel ate all the available information concerning structural details and individual characteristics of the granaries so far excavated, and also to record others which as yet have only been loca­ ted from the air. No attempt has been made here to trace the architectural traditions of the stone granary, as this subject has been extensively covered elsewhere. 1 Nor does the work include consideration of timber military granaries in Britain, as they have recently been the subject of a comprehensive survey. 2 Consideration has been given to the ideas on grain storage expressed by contemporary Roman writers. Also a section has been devoted purely to the problems of grain storage in general, whether in the Roman or modern world, with regard to such factors as temperature control, granary pests etc., factors which determined the design of many distinguishable features of the Roman military stone-built granary. 1

2.

PRINCIPLES AND PROBLEl\1S OF GRAIN STORAGE FAVOURABLE CONDITIONS FOR STORAGE

Grain continues to respire, taking in oxygen and giving off heat, carbon dioxide and water after it has been harvested. In order to preserve it in storage for later consumption it is necessary to slow dO\vn these processes as much as possible. The principal methods in effecting this retardation are to reduce the temperature, the moisture content, and the amount of oxygen available. A major problem in the bulk storage of grain is its susceptibility to infestation by bacteria, moulds, fungi and insects. The grain will remain dormant providing that the temperature and moisture content remain low, but if it is placed in storage whilst too hot or wet it will begin to genninate and the dampness will encourage the activity of bacteria in the surrounding air, resulting in the growth of moulds and fungi which cause it to rot. Reduction of the temperature and moisture content will serve to minimise this activity. Three principal methods are used in modern practice; the cooling of dry ° grain to a temperature of less than 17. 25 C using air blown through ducts on or below the floor by electric fans, the refrigeration of damp grain at 0-7.5°C or the exclusion of oxygen by storage in airtight silos. Insect infestation damages the grain both directly, by eating or contamina­ ting the cereal grains, and indirectly by causing heating of the grain, resulting in deterioration. Initially heating occurs in localised centres, 'hot spots' which gradually merge, increasing the temperature to as much as 4 3°c. The loss of moisture from these areas as the heating intensifies causes it to condense on the outer, cooler areas of the grain and encourages the onset of fungal growth. H unchecked this activity will render the grain unfit for either flour or malting. The main species of insects and mites which occur in granaries today are the saw-toothed grain beetle (Oryzaephilus surinamensis (L.) ); grain weevil (Sitophilus granarius (L.) ); rust red grain beetle (Cryptolestes ferrugineus (Steph.) ;) and the flour mite (Acarus Siro (L.) ). It has been generally be­ lieved that the saw-toothed grain beetle was a relatively modern introduction to Britain caused by the increase in commercial traffic. However, analysis of insect fauna from two sites has revealed its presence in Roman Britain. The saw-toothed grain beetle was found in a well sealed by 4th century building rubble at Barnsley Park, Gloucestershire, and a late 2nd century rubbish pit at Alcester, Warwickshire has revealed evidence for twenty indivictuals in association with four other pests of stored foods; Sitophilus granarius, Stegobium paniceum, Palorus subdepressus and Tenebrio obscu rus.3 The grain weevil bores holes into the cereal grains and deposits eggs in them which hatch into larvae and feed upon the flour; it is usually associated with wheat and barley, and perhaps rye. The saw-toothed grain beetle cannot

2

attack undamaged cereals and can only survive after initial weevil damage, or in grain which includes broken seeds and dust. 4 Competition between the various species is dependent upon moisture and temperature conditions. For example, the grain weevil needs 15°c to develop and a moisture content of 11%, whereas the saw-toothed grain beetle needs 20°c to become active, but can withstand drier conditions. In favourable conditions they can breed and develop extremely rapidly. To prevent the growth of these insects and also moulds and bacteria the moisture content of the grain must be reduced. To prevent any growth it would be necessary to reduce it to 8-10%, but this is not generally practical in a modern storage unit, still less in its Roman counterpart. In order to store grain successfully either in bulk or in closely stacked sacks, without turning it over or introducing any forced ventilation, for a period of nine months to a year, the maximum moisture content possible is 14% at 15.6°c. As the mois­ ture of the grain increases, so the temperature necessary to prevent it from insect activity must decrease. Temperature is vary closely linked with moisture content in regard to in­ sect growth. It is necessary to store grain below a temperature of 15.6°C to eliminate insect activity, but to prevent mould and bacteria growth it must be further decreased according to moisture content. A minimum of only two fully grown grain weevils in a pound of wheat (0.45 Kg) is sufficient to generate heating. Cooling it to at least 15°C is needed therefore to preserve the crop. A more convenient method of storage in which maximum use is made of ventilation to reduce temperature and moisture content is achieved by storage in sacks rather than in bulk. The smaller unit of the sack enables water vapour and heat to dissipate more rapidly, provided that they are not stacked too close together so as to exclude the air. It has been calculated that a 100 Kg bag (2 cwt) open to the air will cool in 25 hours as much as a 3 metre square (10 ft sq) silo will cool in 8 weeks.5 The eggs of the insects can survive for long periods in cold, empty granaries without suffering any adverse effects, becoming active again when storage is renewed and the temperature is favourable.6 Whilst inactive they tend to inhabit cracks in the granary fabric, in crevices and ledges in walls, or in holes in the flooring. 7 To minimise the dangers of infestation to the new crop of grain it is necessary to ensure that the walls are smooth and well plastered, and that the floor is free from cracks and holes which might provide harbourage for insects. Considerable damage may also be caused by the entry of rodents to the granary, the most common pests being the rat (Rattus norvegicus Berk.), and the common mouse (Mus musculus L. ). During the autumn and winter the granary provided ideal food and shelter for such creatures and much harm can be caused by gnawing and contamination. The main methods of combatting these pests before the advent of rat poison must have been primarily concerned with the prevention of entry by plugging holes in the fabric, providing some form of mesh over the ventilators, and blocking holes under the eaves. Birds also injure the grain and the best deterrent would have been to keep the build­ ing as dark as possible to dissuade them from flying in when the doors were opened.

The main requirements for the successful storage of grain both in the ancient and modern periods consist of the prevention of germination and in­ sect infestation by maintaining a lo\\· temperature and moisture content, and the prevention of contamination and destruction by rodents and birds, by denying them any opportunity of access. STRUCTURAL REQUIREl\IENTS FOR GRAI1 r STORAGE Bulk grain exerts complex pressures upon its retaining walls and acts as a 'semi fluid'. It exerts lateral thrust against the walls of its enclosing bins and also against the external granary walls. A vertical pressure is applied to the floor by the sheer weight of the grain; for example, wheat exerts a pressure of 785 kg fu3, and barley, 689 kg;m3 . In addition, another vertical force is added to the walls because of the friction created between the bulk of the grain and the surface of the wall. The relationship between these forces has been expressed by Janssen and simplified by Jamieson. 8 The foundations must be substantial enough to withstand the vertical pres­sures imposed upon the floor. The strength and safety of the foundations are dependent upon the subsoil into which they are dug, and their depth. Rock, compact gravel and firm clean sand provide the safest foundations and will permit a safe maximum load of grain of from 27 .3 3 tonnes/m to 49 .19 tonnes/ m3 upon firm sand to as much as 7 .45-196. 76 tonnes/m3 upon hard rock. In addition to the needs imposed by the actual pressure ·of the grain, the granary must incorporate certain other features. Low temperatures and moisture levels are maintained in a modern example by means of electric fans and air ducts; either above or below floor level. To prevent damp it is necessary to completely waterproof the granary; roofs, gables and eaves should be watertight and the pitch of the roof should be sufficiently steep to enable good drainage of raimvater, 22 degrees is recommended today. Surface water must not be allowed to accumulate in the vicinity, and adequate drainage around the perimeter should be provided to eliminate this. It is also necessary to ensure that there is good access for loading and unloading purposes. There must be sufficient space in front of the loading area for vehicles to turn round and manoeuvre easily. We must assume that the basic properties and problems of grain and other foodstuffs in storage have not changed substantially from the Roman period to the present day. Thus, many of the structural features which are today in­ corporated into granaries to minimise damage to the grain were in use during the Roman period and can be detected in the structural remains of stone built granaries which survive in Roman forts.

4

3 .

CLASS ICAL REFERENCES TO GRA IN STORAGE

S o me i nforma t ion c oncern ing t he c ond it ions n ecessary f or t he s torage o f g ra in a nd o ther f oodstuf fs i n t he Ro man p er iod c an b e o bta ined f ro m c o m ment ators o n a gr icu ltura l t echn iques o f t he C lass ica l wor ld. I n 1 60 B .C. Marcus Ca to r eco m mended t ha t a mix ture o f c haf f w ith t he r es idue o f c rushed o l ives, amurca , s hou ld b e smeared o ver t he i n ter ior o f t he g ranary.

Once t h is s ubstance h ad d r ied h e a ssured h is r eaders t hat

c oo led g ra in c ou ld b e s tored i ns ide q u ite s uccessfu l ly , w ithou t d anger f ro m mice o r weev ils. 9 Varro, wr it ing i n 3 7 B .C. a dvoca ted t hat whea t s hou ld b e s tored i n g rana r ies a bove g round ( sub l im ia ), o pen t o t he d raugh t o n t he e ast a nd n or th s ides i n o rder t o p reven t d a mpness.

He a lso d escr ibed e xa mp les i n H ither S pa in

a nd Apu l ia where g ranar ies were b u ilt a bove g round i n s uch a way t ha t t he w ind c ou ld c oo l t he m ; f ro m b eneath.

b o th f ro m t he s ides , b y means o f w indows , a nd a lso

The wa l ls a nd f l oor s hou ld b e c oated w ith e ither marb le c e men t

o r c lay m ixed w ith c ha f f a nd amurca , b oth t o p reven t d a mage b y i nsects a nd mice , a nd t o make t he g ra in f ir m.

O ther measures t aken b y f armers t o

p reven t d eter iora t ion , a ccord ing t o Varro , i ncluded s pr ink l ing amurca o ver t he whea t , a nd u s ing Cha lc id ian c ha lk o r wor mwood.

1 0

However , i ft he g rain h as a lready b eco me i n fested h e s uggests a c ure. The g ra in s hou ld b e t aken o u ts ide i n t he s unsh ine a nd b ow ls o f wa ter s hould b e p laced a round i ti n t he h ope t ha t ' t he weev ils w i l l c ongregate a t t hese a nd d rown t he mse lves.' 1 1 V itn iv ius , i n t he e ar ly 2 0s B .C. a greed t ha t g ranar ies s hou ld h ave c onc rete f l oors a nd a lso a n or th o r n or th-east a spect i n o rder t o v en t i la te t he g ra in , f or i f i t was n ot k ep t c oo l i t wou ld b e d a maged b y weev ils a nd r oden ts! 2 I n o rder t o k eep g ra in a s d ry a s p oss ib le Co lu mel la ( A. D. 6 0 ) a dvoca ted t ha t g ra in a nd c erea ls s hou ld b e s tored i n v en t ila ted l of ts , wh i lst o i l a nd w ine were k ep t b elow .

He a lso d escr ibed a method o f s torage i n wh ich t he g ranary

w ith a v au lted c e il ing h ad i t s e ar then f loor f irst s oaked w ith l ees o f o i l t hen r a m med d own l ike o pus s ign inu m , a nd t hen o ver la in b y af loor ing o f t i les a nd s and m ixed w ith o i l l ees i nstead o f water.

The wa l ls must b e p lastered w ith

c lay a nd o i l l ees mixed w ith d r ied l eaves o f t he w i ld o l ive, a nd t he j o in t b et ween w a ll a nd f loor must b e wel l s ea led t o p reven t i nsects f ro m b e ing h arboured i n t he c racks.

He warns a ga inst d isturb ing g ra in wh ich i s r ecog-

n ised t o b e i n fes ted f or , r ather t han g et t ing r id o f t he p ests , t hey w i l l o n ly b e d istr ibuted t hrough t he who le mass.

However , i ft hey a re l ef t u nd isturbed

t hey w i l l o n ly b e c oncen tra ted t o ad ep th o f ap a lm 's b read th a nd t he u nderl y ing c rop w i l l b e u nda maged. 1 3 I fl ong t erm g ra in s torage i s i ntended Co lu mel la s uggests t hat t he g ra in s hou ld b e t hreshed t w ice t o d iscourage weev ils. t 4

5

In his Naturalis Historia (A.D. 77) Pliny summarises the main methods grain storage and the controversies between different authorities on the of subject. Some preferred brick granaries with walls a yard thick without any ve ntilators or windows. Others, like Vitruvius, preferred windows facing north or north-east. Some farmers did not use lime in the construction of their granaries because they believed that it damaged the corn. Some gran­ aries were built of timber and supported in pillars to facilitate ventilation, but there were also those who believed that grain shrinks in bulk if the floor is raised. Pliny also recorded the practice of those who thought that they could best preserve the grain by hanging up a toad by one of its longer legs at the entrance of the granary prior to the entry of the corn. Pliny himself was of the opinion that despite the various methods postula­ ted, one of the main factors in the preservation of stored grain was storing it at the appropriate time. It was useless to store if the grain was insufficiently ripened, or when it was too hot, for both factors encouraged pests to breed. He advocated storing grain in the ear as the method by which it was least likely to suffer damage.1 G Although the climatic conditions referred to by these Italian commentators differ from those prevailing in Britain the main principles concerning grain storage remain constant. The principal features which are emphasised by all these authors is the necessity to reduce the moisture content and temperature, and to minimise the activity of insect and rodent pests. It is possible to detect some of the methods of achieving these requirements in the study of granaries built by the Roman army in Britain.

6

4.

A COMPARISON OF EXCAVATED STRUCTURES

Types The predominant type of stone granary found in Roman forts in Britain is the single example, buttressed along its external walls. Other types which occur are variations on this basic type. Two single granaries may be paired, sharing a common central wall as at Hardknott and Benwell ( Figs. 6, 11), or may be linked together either around a central courtyard as at Ambleside and Caerhun (Figs. 6, 7), or with a small space between the partition walls, such as at Housesteads and Templeborough (Figs. 11, 14). A third variation, in which two single granaries are placed end to end has only so far been dis­ covered at Birrens (Fig. 6). The choice as to whether to build single granaries or pair them together seems to have been governed by convenience on individual sites. Ease of access for loading and unloading may have been facilitated by the pairing of granaries, but this seems to have depended upon the choice of each fort builder a and does not seem to reflect their date of construction. Sizes and Proportions Sizes varied considerably from 48 .46 x 13.41 m in the legionary granaries at Chester, to 14.12 x 5.28 m in the fortlet of Croy Hill. The majority ranged from 20 to 30 m in length and from 6 to 10 m in breadth. The double granaries were often almost square units, for example Hardlmott and Templeborough, (Figs. 11, 14), although others such as Benwell and High Rochester (Figs. 6, 11) were more elongated. The width must have been governed to a large extent by the maximum practical roof span available without needi!]-g elaborate and inconvenient internal supports. The length seems, in most cases to have been dependent upon the distance available between the via principalis and via quintana. Despite the variations in dimensions the proportions (Appendix 4) appear quite constant and the ratio of length to breadth is approximately 3-4:1, although there are some notable variations, for example at Camelon, where the proportions are 5·3 or Gelligaer, 2:1. Construction One of the characteristic features of the Roman military stone-built granary is the substantial nature of its construction. Walls varied in thiclmess be­ tween O. 76 m and as much as 1.30 m. The actual construction of the walling differed: some examples consisted entirely of mortared ashlar blocks, such as Chester and Penydarren, whilst others were drystone built, as at Old Church, Brampton and Slack. Other examples consisted of a facing of ashlar with a mortared rubble core, visible at Drumburgh, Corbridge and Templeborough. The majority had buttresses built along the long walls, and often also at the ends, usually an average of one metre square, and well bonded with the wall. 7

They were invariably regularly spaced, the distances between them varying from 1. 50 m to 3 m. Where sufficient evidence survives it appears that they were paired across the width of the structure to support regularly spaced roof trusses. The dimensions of external walls and buttresses are tabulated below (Table 4, p.55). A small number of granaries were unbuttressed; Bar Hill, Caernarfon, Corbridge Phase 1 (3 examples), Slack and Whitley Castle (Figs. 6,7,9,14). Current thinking on the Corbridge examples suggests that they were probably half-timbered above masonry sleeper walls; and they may have supported timber clad roofs rather than heavy tiles. The Bar Hill, Caernarfon and all three Corbridge unbuttressed granaries are Antonine; the dates of Slack and Whitley Castle are uncertain. Foundations consisted predominantly of clay and cobble packed foundation trenches, either following closely the line of the walls and projecting buttres­ ses, or extending to the outer face of the buttresses; e.g. Balmuildy and Newstead. The granaries at Chester had foundations of pebbles and sandstone in rock-cut trenches. Several examples were founded upon broad stone flagged rafts overlying rammed clay and cobbles; such as Ambleside, Benwell, Cramond, Gelligaer II, Haltonchesters, 66 and Old Church, Brampton. Floor Supports and Flooring The floors of the horrea could be supported in three different ways: either by means of transverse walls, longitudinal walls or pillars. Alternatively, the floor may not have been raised at all. Transverse sleeper walls were usually built approximately O. 61 m wide and between O. 70 m and O. 90 m apart. They vary in number from six at Gelligaer II to seventeen at Castell Collen. Rickman has pointed out that the transverse sleeper wall was used first in the Trajanic stone granaries of the Welsh auxiliary forts of Gelligaer II, Castell Collen and Penydarren, (Figs, 8, 10, 13) and he believes that this method of construction reflects an early copying in sto e o e. o s use ·n ui ing tim er granaries such as Fendoch or Inchtuthil.16 Later examples occur at Great Chesters, which is possibly Hadrianic (Fig. 11), in the I, ntonine single granary at Lyne (Fig. 12), and into the late 170s A.D. in the east granary at Corbridge in its third structural phase (Fig. 9). There are slight variations in the construction of transverse sleeper walls: some examples were continuous, such as at Castell Collen and Lyne (Figs. 8, 12), whilst others had a central break, probably to enable good circulation of air, as at Gelligaer II and Corbridge Phase 3. (Figs. 9. 10). Penydarren, on the other hand, seems to incorporate both features (Figs. 13). Gelligaer and Penydarren also provide tolerably good evidence for the presence of timber flooring, and this combination of transverse sleeper wall supporting a timber floor seems to represent the earliest traces of stone­ built military horrea in Britain, of the Trajanic-Hadrianic period. Several of the granaries studied did not exhibit any form of raised floor at all, not because the remains had been ploughed or robbed, or missed by incompetent excavation, but because the floors were laid directly upon the ground and were not provided with elaborate ventilation systems. Brecon

Gaer a nd Caersws I h ad f l agged f loors l a id u pon t he n atura l s ubso il.

Caer-

n ar fon a nd Te mp leborough h ad b eaten c lay f loors , a nd Caerhun s t il l r eta ined 3 -7 cm o f d eco mposed c e men t , r em in iscen t o f t he g ranary f loor d escr ibed b y Co lume lla ( see a bove, p . 5 ) . The u se o f s tone f lagg ing was s uf f ic ien t t o c oun teract r is ing d a mp a nd t here was n o n eed t o r a ise i to f f t he g round , a s was n ecessary w ith t imber f loors.

I t i s p oss ib le t hat t hese f loors r epresen t

l ater mod if ica t ions t o t he g ranar ies i n wh ich a l l t race o f r a ised f loor s uppor ts h ad b een r e moved.

I t i s e ven p oss ible t hat i n s o me e xa mp les t he f loor was

r a ised n ot b y means o f s tone wa l ls o r p iers , b u t b y t imber p osts, s uch a s t hose d iscovered i n t he G er man f or ts o f Ne iderb ieber a nd We issenburg , o ver looked d ur ing e xcava t ion.

1 7

Pro fessor G . D . B . J ones h as l ocated p ostho les 1 .25 m

a par t r unn ing p ara l le l b oth w ith t he i n terna l f ace o f t he e x terna l wa l l a nd w ith al ong itud ina l s leeper wa l l i n t he g ranary a t Pu mpsa in t. 1 8

They h ave b een

i n terpreted e ither a s p art o f at imber f ra me t o t i e t he r oof b ea ms , o r t o s upp or t at imber f loor.

I t i s d if f icu l t t o s ee why t he s tone s leeper wa l ls s hou ld

n eed t o h ave b een s upp le men ted b y t imber p osts wh ich wou ld h ave a r elat ive ly s hor t l i fe i n c o mpar ison w ith t he ir s tone c oun terpar ts ;

we c ou ld b e d eal ing

h ere w ith a n e ar l ier s er ies o f t imbers r ep laced s ubsequen t ly i n s tone, o r e ven t he b ases o f s ca f fo ld ing p osts wh ich must h ave b een u sed i n t he g ranary 's c ons truc t ion. I ti s p oss ib le t o g ive o n ly v ery a pprox i mate d ates t o t he e xa mp les o f g rana r ies w ithout r a ised f loors.

T e mp leborough i s t hought t o h ave b een c onstruc ted

i n s tone a f ter A . D . 1 00 ,1 9 Brecon Gae r a l ter A . D . 1 40, Ca er sws U l a te Hadr ian ic-An ton ine a nd Caerhun a nd Caernar fon t o b e p oss ib ly o f An ton ine d a te 2 0 By f ar t he most c o m mon method o f r a is ing g ranary f loors i n Br ita in was t he u se o f t he l ong itud ina l s leeper wa l l ( p la te I B ). The wa l ls may b e c on t inuous , a s a t A mb les ide , Bar H i l l , Chester , Lyne a nd Newstead ( F igs. 6 , 8 , 1 2 ) , o r may h ave h ad b reaks a t r egu lar i n terva ls c orrespond ing t o t he p os it ions o f t he v en t ilators t o p rov ide a n a dequate c ircu la t ion o f a ir , s uch a s B irrens , Corbr idge Phase 4 , Rough Cast le a nd S outh S h ields ( Severan ) ( F igs. 6 , 9 , 1 4 ) .

Another v ar ia t ion i s t he u se o f o n ly o ne c on t inuous l ong itud ina l

s leeper wa ll, r unn ing d own t he c en tre o f t he b u i ld ing , e xh ib ited a t O ld Church , Bra mp ton ( east ) a nd R ibchester ( nor th ) ( Fig. 1 3 ).

I t i s n ot c lear , h owever ,

j us t h ow v a l id t h is d ist inct ion i s b ecause t here i s t heposs ib il ity t hat o ther p ara l le l s leeper wa lls may h ave o r ig ina l ly e x is ted , b ut h ave b een s ubsequen t ly r obbed o r s i mp ly missed b y t he e xcavators.

The n u mber o f p ara l le l l ong i-

t ud ina l s leeper wa l ls v ar ies f ro m f our a t S outh S h ie lds ( Severan ) t o e ight a t Corbr idge ( east , Phase 4 ). T he d ate r ange f or t h is method o f f loor s uppor t v ar ies f ro m t he p oss ib le Hadr ian ic e xa mp les a t O ld Church , Bra mp ton , t he e ar ly s econd c en tury a t Ches ter , An ton ine e xa mp les i nclud ing Cadder , Ca melon , Lyne , Newstead a nd Rough Cast le, t o t he S everan e xa mp les a t Corbr idge Phase 4 a nd S outh S h ields.

Both t imber a nd s tone f loor ing s ee ms t o h ave b een u sed ;

f loors h ave b een s ugges ted f or I lk ley a nd R ibches ter ( nor th ).

t imber

O thers h ad

f lagged f loors , s uch a s Rough Cast le ( Anton ine ), a nd B irdoswa ld , Corbr idge a nd S ou th S h ields i n t he S everan p er iod.

Wha t l i t t le e v idence we h ave s ug-

g es ts t ha t t he s tone f lagg ing o f ar a ised f loor may b e more c haracter ist ic o f An ton ine o r S everan c onstruct ion t han o f a n e ar l ier p er iod. 9

Af our th method o f f loor c ons truc t ion was u sed , i n wh ich s tone p i l lars, a rranged i n p ara l le l r ows , s uppor ted t he f l oor. was u sed o n ly i n frequent ly ;

( P la te m A ).

Th is method

i n f ac t o n ly f our e xamp les a re k nown i n B r ita in ,

i n marked c on trast t o t he ma jor ity o f G er man e xa mp les i n wh ich t h is me thod o f f loor s uppor t p redo m ina ted.

2 1

Exa mp les h ave b een f ound a t Cas t lecary .

Houses teads, R ibchester ( sou th ). a nd S outh S h ie lds ( doub le g ranary ).

H ouse-

s teads , R ibchester a nd S outh S h ie lds u sed s quared s tone p i l lars, wh i ls t a t Cast lecary l arge b ou lders 2 0-45 cm i n s ize w ere u sed.

( F igs. 8 . 1, 1 3. 1 4 ).

The n or th g ranary a t Housesteads r evea led s quare s ockets i n t he l ong w a lls t o l ocate t he c ross me mbers o f at imber f l oor. u pon wh ich t he f loor j o ists w ou ld h ave r ested.

B e low t he m p ro jected a l edge , As im ilar l edge r an r ound t he

i n ter ior o f t he s outh g ranary a t R ibches ter , s urv iv ing t o ah e ight o f 1m . A t Housesteads v en t ila tors w ere p rov ided i n t he l ong e x terna l wa l ls wh ich c orr esponded w ith g aps b etween t he r ows o f p i l lars.

( Plate I l IB ).

P il lars were

a lso u sed i n t he H adr ian ic d oub le g ranary a t Hardknot t ( f ig . 1), b u t h ere o nly o ne c en tra l r ow w as r evea led i n e ach h a l f , c ons is t ing o f s even p iers. Da t ing o f t hese s tructures s ee ms t o b e c on f ined t o t he m id s econd c entury ; Housesteads a nd S outh S h ie lds a re H adr ian ic, R ibchester i s u ndated , a nd Cast lecary i s o f An ton ine c onstruc t ion. Exa m inat ion a nd c o mpar ison o f f loor s uppor t me thods d oes s ee m t o s ugges t as equence o f c ons truct ion t echn iques.

T he e ar l iest e xa mp les , o f T ra jan ic-

Hadr ian ic d ate , u t i l ised t ransverse s leeper wa l ls ;

t ota l a bsence o f ar a ised

f loor i s f ound p redo m inan t ly i n Hadr ian ic-An ton ine c on tex ts , a s i s t he u se o f p i l lars.

A lthough l ong itud ina l s leeper wa l ls were p resen t i n t he Hadr ian ic

p er iod t hey s ee m t o c ont inue i n to t he t h ird c entury , a nd w ere u sed e xc lus ively d ur ing t he S everan p er iod.

A lthough s o me s or t o f s equence d oes s eem t o

emerge i ti s v ery d if f icu l t t o p inpo in t i tw ith a ny p rec is ion , o r t o r ea l ly a ssess i t s v a l id ity . The s yste ms w ere n o t mutua lly e xclus ive.

T he Hadr ian ic g ranary a t

Ha ltonches ters c on ta ined n or th-sou th s leeper wa l ls i n t he n or thern p ar t , a nd e ast-west wa l ls i n t he s outhern p ar t , wh ich a ppeared t o b e c on te mporary . S im ilar ly t he u nhut tressec l g ranary u nder ly ing S i te

a t Corhr idge h ad t wo

l ong itud ina l s leeper wa l ls i n t he western h a lf, a nd s ix t ransverse w a l ls i n t he e ast ( An ton ine ).

The

u nf in ished w est g ranary o f Phase 3 a t Corbr idge

a lso c on ta ined t wo c on te mporary s ys te ms o f s leeper wa l ls.

( Fig. 9 ) . T he

s ing le g ranary a t Lyne h ad t ransverse wa l ls wh ilst t he l arge d oub le g ranary h h ad l ong itud ina l w al l ing .

R ibchester a lso e xh ib its t hese v ar ia t ions f or o ne

g ranary h ad l ong itud ina l wa l ls , a nd t he o ther p il lars. S o f ew s tructura l d eta ils a re o f ten g iven i n t he e xcava t ion r epor ts r ecordi ng g ranar ies t ha t i ti s d if f icu lt t o b e s ure whether t he e xa mp les wh ich w ere u ncovered a nd p lanned a re i n f act c on te mporary , o r whether t he f or t h as y ie lded i t s f u l l c o mp le men t o f g ranar ies.

I t i s n ecessary t o k now much more

a bou t t he h istory o f e ach i nd iv idua l s tructure a nd i t s r elat ionsh ip w ith o ther b u ild ings i n t he f or t.

One may h ave b een e n t irely r ef itted o r d e mo l ished , o r

a n e x tra o ne a dded a t ap ar t icu lar p er iod , a nd i f s uccess ive r ebu ild ing c ould b e d etected i tm igh t b e p oss ib le t o r ecogn ise c hanges , f or e xa mp le i n t he methods o f f l oor s uppor t , o r o ther s ign if ican t f ea tures a t s pec if ic d a tes. There i s o n ly o ne e xa mp le wh ich e xh ib its t hese c haracter ist ics, t he p a ir o f

1 0

g ranar ies f ro m Corbr idge wh ich e xh ib it 4 s tructura l p hases. i th as b een p oss ib le t o d etect a s uccess ion o f b u i ld ing .

A t Newstead

A lthough b oth n or th

a nd s ou th g ranar ies h ad s im ilar c obb led f ounda t ions , t he s ou thern e xa mp le was c ons tructed w ith we l l d ressed b locks o f s andstone , s how ing n o s igns o f mod if ica t ion , wh ilst t he f abr ic o f t he n or th g ranary c ons isted o f s andstone , b locks o f b lue g reywacke f ro m t he r iverbed , a nd p ieces o f r eused t i le a nd q uern ;

f actors i nd ica t ing r econs truct ion .

Fro m t h is e v idence t he e xcava tor ,

Mr. J ames Cur ie was a b le t o d educe t ha t a lthough b oth g ranar ies h ad s tood s i mu ltaneous ly , a t al ater d ate , p erhaps w hen t he g arr ison was r educed t he n or th g ranary was d e mo l ished b u t r econstructed l a ter i n t he f or t 's h istory t o c o inc ide w ith t he r ein troduct ion o f al arger g arr ison. 22 Ven t ila tors Ven t i la tors w ere p ierced t hrough t he e x terna l wa l ls i n o rder , i n c on junct ion w ith a r a ised f loor , t o a ch ieve a g ood c ircu lat ion o f c oo l a ir.

They were

u sual ly p laced b etween e ach p a ir o f b u ttresses o n t he l ong wa l ls b ut t here a re v ar ia t ions , s uch a s Cast lecary ( F ig. 8 ) , where o n ly t he t hree c en tra l b ays a re p ierced w ith v en t ila tors.

The o pen ings v ar ied i n max i mu m w id th f ro m

0 .75 m a t Chester t o 0 .30 m a t S outh S h ie lds. o r were c o mp lete ly r ectangu lar .

T hey e ither s p layed i nwards

S evera l e xa mp les d isp lay s ubsequen t r e-

d uct ions i n w id th b y b lock ing ; a t G el l igaer t he v en t ilators w ere r educed f ro m I m t o 0 .60 m, a nd a t Ba lmu ildy f ro m 0 .45 m t o 0 .22 m. S uch l arge a per tures w ould s carce ly h ave e xc luded r odents a nd o ther sma l l a n i ma ls f ro m e n ter ing t he b ase men t b e low t he g ranary f loor , a nd s p il lage o f g ra in i n to t h is a rea , e spec ia l ly t hrough c racks i n aw ooden f l oor wou ld h ave p rov ided a g ood h arbourage f or t hese p es ts.

I t mus t t herefore h ave b een n ec-

e ssary t o c over t he v en t i la t ion s l its w ith a wooden o r i ron g r il l t o p reven t t h is. There s ee ms t o b e l i tt le e v idence f or t he s urv iva l o f i ron t races i n t hese p os it ions a nd i t must b e a ssu med t ha t t imber was u sed i nstead . J r . h is e xcavat ions a t Cadder i n 1 929-31 J ohn C larke d etected a ' b lack l ayer ' 8 cm t h ick b es ide t he wa l ls i n wha t a ppeared t o b e t wo d ist inct l ayers. He d rew c o mpar isons w ith o ther s i tes wh ich h ad s im ilar l ayers a ssoc ia ted w ith t he e x ter ior o f g ranar ies.

A t C ast lecary , ad oub le l ayer o f c oa l d ross was d e-

t ected , a t S lack a l ayer o f b urn t mater ia l o ccurred wh ich was n ot b urnt a ga in . S im ilar ly t here w ere s trong s igns o f b urn ing o u ts ide t he s econd v en t ila tor f ro m t he s ou th a ng le o n t he s ou th-west wa l l a t Castel l Co h en. C larke s uggests t ha t t hese l ayers r epresen t p er iod ica l a t te mp ts t o smoke o u t v er m in. 2 3 I n v iew o f t he p rob le ms wh ich v erm in must h ave c aused b y e n ter ing t he v en t ila t ion c hann els i td oes s ee m f eas ib le t hat o ccas iona l ly when t he g ranary was emp ty , t he v ent ilators were p erhaps b locked u p a nd a f ire l i t a t o ne e nd i n o rder t o smoke t he m o u t . A c oup le o f t he g ranar ies s tud ied p ossessed a n e n trance i n o ne o f t he s hor t s ides, n o t l arge e nough f or a p roper d oorway , b u t n ever theless p rov ided w ith s o me f orm o f d oor fra me, w h ich was s ubsequen t ly b locked.

One o ccurs i n t he

west g ranary a t Corbr idge ( Phase 4 ), a t Hardknot t , a nd p oss ib ly a lso a t Rough Cast le ( F ig . 1 1, 1 4 ). The e xcava tor o f t he Corbr idge e xa mp le s uggested t ha t t h is may h ave b een u sed t o p rov ide a ccess d ur ing t he b u ild ing 's c onstruct ion a nd a lso l a ter f or p er iod ic c lean ing , o r p erhaps t o k eep r oden ts a t b ay. 24

1

L oad ing p la tfor ms, p or t icos , e n trances a nd d ra ins The s hor t e nd wa l l o f t he g ranary w as i nvar iab ly u sed t o p rov ide a ccess a nd t here i s n o e v idence f or d oorways b e ing s i tua ted i n t he l ong w a l ls.

S ev-

e ra l g ranar ies p ossessed s tone-bu il t l oad ing p la t for ms c onstructed a ga inst o ne o f t hese e nd wa l ls , d es igned t o f ac il ita te t he h and l ing o f l arge q uan t it ies o f g ra in.

I n s o me i nstances t hey w ere i ncorpora ted w ith a p or t ico t o p rov ide

e x tra s helter d ur ing l oad ing a nd u n load ing.

We l l p reserved e xa mp les h ave

b een r ecorded a t Corbr idge, Hardkno t t , R ibches ter , Rough Cast le a nd Rudc hester ( Figs. 9 , 1, 1 3, 1 4 ).

T hey were o f s o l id masonry c ons truc t ion a nd

p rotruded b etween t wo a nd t hree metres.

O ther s tructures were l ess s ub-

s tan t ia l , f or e xa mp le a t Cast lecary a nd S ou th S h ields ( Severan ), w here o ne o f t he e nd wa l ls was d oub led i n t h ickness i n o rder t o f or m a l oad ing p la t for m. Another method o f c onstruct ion i s s een a t G el l igaer H ( F ig. 1 0 ) where t he l oad ing p la t for ms w ere b u i lt a cross t he f u l l w id th o f t he g ranary , a nd s i tuat ed a t b oth e nds.

T hey c ons isted o f a n o uter f ra mework o f wel l-dressed

s tones , i nf i lled w ith r ubb le, a nd f l agged. Exa m ina t ion o f worn a nd u nworn f lagstones h as l ed t he e xcavator t o s uggest t hat a p or t ico may h ave o r ig ina lly b een c onstructed o n t he ir

p er i meter .25

There a re s evera l e xamp les

where t races o f f ounda t ions o f l oad ing p la tfor ms h ave b een l ocated a l though t here i s l i tt le e v idence a s t o t he ir n ature , f or e xa mp le a t Cadder , C appuck , I I lk ley a nd S lack . I n t he ma jor ity o f g ranar ies e xcava ted n o t races o f l oad ing p la t for ms h ave b een . r ecorded.

I t i s p oss ib le t ha t i n many i nstances t imber p la t forms were

u sed , l eav ing o n ly t he r e ma ins o f p ostho les wh ich may h ave b een o ver looked d ur ing e xcava t ion.

On t he o ther h and , i t may s o met i mes h ave b een n ecessary

t o u t il ise a l l t he s pace a l lo t ted b etween t he v ia p r inc ipa l is a nd v ia q u intana f or t he c onstruct ion o f t he g ranary , l eav ing i nsuf f ic ien t e x tra s pace t o a l low a p la t for m t o p rotrude.

On g ranar ies w ithou t e nd b ut tresses i t wou ld h ave b een

q u ite p oss ib le t o d raw 4 c ar t a longs ide a nd u n load i t s c on ten ts , w ithout t he a id o f a n i n ter med ia te p lat form .

Where p ro trud ing e nd b u t tresses d o o ccur t h is

wou ld h ave b een imposs ib le a nd i tw ou ld h ave b een n ecessary , i n t he a bsence o f al oad ing p lat for m , t o p er form t he r e lat ive ly d i f f icu lt manoeuvre o f b acki ng t he c ar t i n to t he d oorway. The l oad ing p la tform was o n ly a ct ing a s a n e x terna l p ro ject ion o f t he i nt erna l f l oor , a nd i t wou ld h ave b een n o more d if f icu l t t o l i f t s acks o f g ra in d irect ly f ro m t he c ar t t o f l oor l eve l t han f ro m t he c ar t o n to a l oad ing p la tf orm.

The ma in a dvan tage i s t ha t t he p rov is ion o f ap or t ico e nab les t he b u lk

s tores t o b e o f f-loaded i n r ela t ive ly s hel tered c ond it ions.

I t i s p oss ible t o

e nv isage t he d oors o pen ing o utwards t o e nc lose t he s ides o f t he b ay , p rov id ing af orm o f w ea therproof t unne l t hrough wh ich t he g ra in c ou ld b e t aken i n to t he i n ter ior o f t he g ranary . D or t icos h ave b een l oca ted a t Benwel l , Corbr idge, Newstead , S outh S h ie lds ( Hadr ian ic ) a nd T e mp leborough.

A t Benwe l l ( F ig . 6 ) , s ix r ectangu lar p iers

r e ma ined , c onstructed u pon s p layed b ases , i n f ron t o f t he b u ild ing . Corbr idge ( Phases 3 a nd 4 ) e igh t c o lu mn b ases r e ma ined.

A t

I n b oth c ases t he

w id th b etween t he c en tra l p iers was g reater t han b etween t he l a tera l o nes , t hus g iv ing more r oo m f or c ar ts t o manoeuvre t o r each t he c en tra l d oors. N ear t he s outh-west c orner o f t he s outh g ranary a t Newstead ( Fig . 1 2 ) was 1 2

f ound a s ing le c o lu mn w ith a c ircu lar b ase , a t ad istance o f 0 .65 m f ro m t he west wa l l.

I t was b el ieved b y t he e xcavator t hat t h is was t he s o le s urv ivor o f

ap or t ico o r ig ina l ly s i tua ted o n t he west s ide o f t he g ranary . 26

T he Hadr ian ic

d ouble g ranary a t S outh S h ields ( F ig. 1 4 ) r evea led t he r e ma ins o f t hree s quared p illar b ases.

P erhaps t he b est s urv iv ing e xa mp le i s t ha t o f T e mp leborough

( Fig. 1 4 ) where a p or t ico was b u ilt a long t he s outh a nd e ast s ides , c ons ist ing o f f our a nd s even c o lu mns r espect ive ly. A lthough s o f ew p or t icos h ave b een l oca ted i n a ssoc ia t ion w ith g ranar ies i t i s p oss ib le t hat many more may h ave o r ig ina l ly e x isted.

T he c o lu mns may

h ave b een c onstructed o f t imber , a nd t he v erandah b onded t o t he g ranary a bove a l evel a t wh ich a ny e v idence wou ld s urv ive a rchaeo log ica l ly. s ocke ts may wel l h ave b een o ver looked i n e xcavat ion.

T i mber

I ft he e xcava tor was

merely f o l low ing t he wa l ls o f t he g ranary h e i s u n l ikely t o h ave f ound a p or t ico b u ilt a t ad istance o f s o me metres f ro m t he e x terna l wa l l. c ase i n t he d etect ion o f a ssoc ia ted

d ra ins.

Th is i s a lso t he

The e xa mp le a t Corbr idge s hows

q u ite c lear ly a n e nc irc l ing d ra in ( F ig. 9 ) , b ut a s t hey were b u il t t o d ra in wa ter away f ro m t he e aves t hey a re o f n ecess ity b u ilt a t s o me d istance f ro m t he g ranary w a l l, a nd t hus i f al arge a rea i n t he v ic in ity o f t he g ranary was n ot e xa m ined s uch f eatures may w el l h ave r e ma ined h idden. r evea led g ranary d ra ins ;

S evera l s i tes h ave

e i ther s i mp le o pen g u t ters s uch a s a t Bar H i ll a nd

B irrens , o r s tone f lagged , s uch a s Corbr idge a nd T e mp leborough.

( F igs.

6 , 9 , 1 4 ). Few o f t he e xa mp les s howed a ny e v idence o f s teps o r e n trances.

The s teps

a nd t hresho ld o f t he n or th g ranary a t Housesteads s t il l s urv ive a nd t here was a lso a f l ight o f s teps 2 .89 m b road i n t he e ast g ranary a t Benwel l. ( south ) a nd S lack a lso h ad s teps r e ma in ing.

R ibchester

The l ow i nc idence o f s urv iva l o f

e v idence f or e ntrances may wel l b e d ue t o t he f ac t t ha t i n many e xa mp les o n ly t he f ounda t ions s urv ived s ubsequen t s tone r obb ing a nd c u l t iva t ion , b u t t he wa lls wou ld h ave h ad t o s urv ive t o t he h e igh t o f t he f loor l eve l b efore s uch e v idence c ou ld b e e xpected. S it ing w ith in t he f or t The ma jor ity o f g ranar ies were l oca ted w ith in t he c en tra l r ange o f p r inc ipa l b u ild ings.

Both s ing le a nd d oub le g ranar ies were u sua l ly s i ted o n o ne o r b oth

s ides o f t he p r inc ip ia , w ith t he ir s hort a x is p ara l lel w ith t he v ia p r inc ipa l is. There a re v ar ia t ions o n t h is g enera l p icture.

For e xa mp le , a l though t he s ing le

g ranar ies a t G el l igaer a re s itua ted i n t he c en tra l r ange o n e ither s ide o f t he p r inc ip ia t hey a re n ot im med iate ly a d jacen t b ut a re s i ted n ex t t o t wo o f t he g a tes. S o me e xamples d o o ccupy a c en tra l p os it ion b ut i nstead o f f lank ing t he p r inc ip ia t wo s ing le g ranar ies may b e b u il t n ex t t o e ach o ther , w ith t he ir l ong a x is p arel le l w ith t he v ia p r inc ipa l is , f or e xa mp le, B irdoswa ld , Caernarvon a nd Caste l l C o llen , a nd a lso t he d oub le a t T e mp leborough.

One o f t he

ma in f ac tors

g overn ing t he s i t ing o f t he g ranar ies must h ave b een c oncerned w ith c onven ience ; t he p rocess o f l oad ing a nd u n load ing s upp l ies must h ave b een i nconven ien t t o t he r unn ing o f t he f or t a nd t he ir s i t ing wou ld h ave b een c hosen t o m in im ise t he o bstruc t ion c aused. Add it iona l g ranar ies w ere s i ted i n v ar ious p os it ions.

T he d oub le g ranary

a t B irrens , ( Fig . 6 ) f or e xa mp le , was s i tuated o n t he o ppos ite s ide o f t he v ia

1 3

principalis to the single ones, \\ith its long axis parallel. At Drumburgh a granary is sited in the north-west angle of the fort, at Chester-le-Street there is one placed next to the east gate, both examples presumably supplementing centrally positioned granaries. In the legionary fortress at Chester three of the granaries have been located in the praetentura, next to the porta principalis dextra. T heir situation out­ side the principal range seems to have been dictated by the necessity to be as near to the harbour gate as possible for greater east in unloading supplies. 27 Another variation in the general pattern is provided by the granaries at South Shields. In the Hadrianic period the double granary was situated in the prin­ciple range, next to the south-,\·est gate, but during the Severan period the entire fort was converted into granary space (Fig. 3), in which twenty singles were constructed, each with their short axis parallel with the via principalis, and arranged in three parallel rows in the praetentura, principal range and half of the retentura. The eccentric position of the recently exca,·ated granary at Bearsden demonstrates that sometimes the siting \ms dictated by the topography of the site, in this case a steep north-south slope which had necessitated the construction of the granary along the slope. 28

14

5 .

SF I t T JCTURAL ASPECTS , AND THEIR I NTERPRETAT ION

The s urv iv ing s tructura l r e ma ins o f t hese g ranar ies i l lustra te many o f t he d ist inct ive

f eatures wh ich were d es igned b y t he Ro man mi l itary e ng ineers t o

o verco me t he p roble ms o f g ra in s torage, o ut l ined a bove. 29 Ma in tenance o f al ow t e mperature was a ch ieved b y t he a ir c hanne ls p rov ided b e tween t he s uppor ts o f t he r a ised f loor wh ich , l inked t o v en t ila tors i n t he e x terna l wa l ls , p roduced a c oo l t hrough d raugh t o f a ir.

T he c o mb inat ion

o f s tone wa ll ing a nd s tone f l agg ing wou ld h ave c on tr ibuted s ign if ican t ly t o t h is r efr igera t ion e f fect , a nd w ould a lso h ave p reven ted r is ing d a mp f ro m d a magi ng t he g ra in.

However , e ven o n a wa terproof f l oor t he b o t to m l ayer o f g ra in

t ends t o g et d a mp b ecause o f t he c h il l ing , a nd i t wou ld h ave b een a dv isab le t o s tore t he g ra in o n d unnage , wooden g rat ings o f s o me k ind , t o p reven t t h is. 30 A s uggest ion h as o f ten b een made i n t he p ast t ha t t he t h ick b u t tressed walls w ere n ecess ita ted b y t he g rea t l atera l t hrust i mposed b y t he l oose g ra in s tored w ith in. 3 1

Wi ll ia m B u l mer h as p o in ted o ut , h owever , t hat t he p ressures

e xer ted u pon t he e x terna l w a l ls wou ld h ave b een n o g rea ter t han t hose i mposed u pon t he s ides o f i n terna l t imber b ins.

He p ostu la tes t ha t t he ma in s treng th

o f t he b u ild ing was p rov ided b y as er ies o f s trong masonry p iers s uppor t ing t he r oof t russes i n wh ich t he l eng ths o f wa l l ing b etween , s truc tura l ly w eake ned b y t he i nser t ion o f u nder f loor v ent ila tors a nd h igh l eve l l ouvred o peni ngs , p er for med mere ly t he f unct ion o f wea ther p roof ing . 32 I n a n a t te mp t t o t est t he v a l id ity o f t hese c onclus ions c a lcu lat ions w ere made, t ak ing t he west g ranary a t Corbr idge a s a n e xa mp le, i n o rder t o a ssess t he s truc tural s treng th o f t he wa lls a nd b ut tresses.

Append ix I s hows t ha t t he

walls o f t he Corbr idge e xamp le were q u ite a dequate t o w ithstand t he p ressures o f g ra in s tacked t o ah e igh t i n e xcess o f 3 metres.

Thus, a l though b u lk g ra in

d oes e xer t c o mp lex p ressures o n i t s r eta in ing wa l ls , i ti s c lear t hat t he w id th o f t he w a l ls o f t he g ranar ies s tud ied were q u ite s uf f ic ien t t o c oun teract t he l atera l t hrust o f t he g ra in . The p rov is ion o f e x terna l b ut tresses wh ich a re p resen t i n most o f t he g ranar ies u nder c ons idera t ion , d o n ot s ee m t o b e l i nked p r i mar ily w ith r es ist ing t he p ressures e xerted b y t he g ra in.

I t i s more p robab le t hat t he ir

f unct ion l i es i n s uppor t ing t he h eavy t i led r oof a nd t he c o mp lex o f t imber s upp or ts ( F ig. 1 ).

The Corbr idge e xa mp le s hows q u ite c lear ly t hat t he b u t tres-

s es a re p a ired a cross t he w id th o f t he b u ild ing a nd t hey p robab ly b ore t he ma in h or izon ta l r oof t imbers.

T he we igh t o f at i led r oof o f o ne o f t hese b u ild ings

must h ave b een c ons iderab le ( F ig. 2 ).

Quan t it ies o f t i le d ebr is h ave o f ten

b een f ound d ur ing e xcava t ion , b oth t egu lae a nd i mbr ices.

T iles were p resen t

a t s evera l s i tes i nclud ing Ba l mu i ldy , Chester a nd G e ll igaer .

S tone r oof ing

s labs h ave b een r ecovered f ro m I lk ley a nd Ha ltonchesters, a nd s late f ro m A mble s ide.

1 5

The approximate \'eight of the roof at Corbridge has been estimated, based upon measurements and weights of se\·eral examples of tegulae and imbrices from the collection of the National Museum of Wales. (See Appendix 2.) The minimum weight of a tiled roof would be 28 tons, and, if the weight of timber (oak) trusses and supports is taken into consideration, it may be increased by at least a further 12 tons to make a minimum total of 40 tons. Calculations to assess the smallest cross section of buttresses required to support such a roof weight have been included in Appendix 3. The results from two of the examples examined, Corbridge and Castlecary, show quite clearly that the buttresses alone ,,·ould have been sufficiently strong to support the conjectured roof weights. Thus it is concluded that, although the problems of lateral thrust and weatherproofing must be taken into account, the prime function of the heavy buttressing was to uphold the heavy tiled roof. Other stone-built structures within the Roman fort must also have been tile-roofed, especially the principia and praetorium, but very few exhibit the characteristic buttressing of the granaries, \\·ith the exception of Birrens, Camelon, Cramond and Crawford II. It is possible that the basic courtyard plan of these buildings incorporating many more load bearing internal partitions and presenting smaller expanses to be roofed, presented fewer problems. Tiled roofs would have made the granaries weatherproof, and in addition, an efficient method of drainage was essential to eliminate surface water and dampness in the vicinity of the granary. The roofs were also externally fire­ proof, a very important factor; destruction of the granary would render the garrison extremely vulnerable, especially those in outlying areas. It has been suggested that forts \\ hich \\"ere built entirely of timber, for example Inchtut­ hil, needed special precautions to eliminate the fire risk and thus the six granaries vvere not grouped together in the usual way but dispersed into op­ posite parts of the fortress to minimise the risks.33 The granary surviving to the greatest height which has so far been excavated is the one standing 2.75 m high in the Classis Britannica fort at Dover. Unfortunately it has been impossible to obtain any information concerning this structure except that "half way up the wall was a beam slot and various soffits", which has led the excavator to postulate a second storey. 34 Similarly, it has been suggested that the insertion of seven large pillars along the central axis of the east granary at Corbridge \\"aS done either to strengthen a sagging roof, or possibly to support a second floor. 35 The case for a second storey must be considered carefully. The thickness of the walls alone would easily be sufficient in many cases to confine the pressures of the grain, and the heavy buttressing tends to look disproportionate when a reconstruction is attempted, which may suggest the presence of a second floor. The need to store other foodstuffs such as vegetables, cheese, wine, meat and olive oil may have taken up extra space in a loft or second storey.36 Several of the granaries studied have revealed external areas of cobbling against one of the long walls; features interpreted by their excavators as foundations for loading platforms. They have been observed at Caerhun, Mumrills and Old Kilpatrick. The position of these features against the long walls makes their interpretations as loading platforms unlikely. They may represent the foundations of stair­ cases leading to an upper floor although one might imagine that, had staircases 16

e x isted , t hey wou ld h ave b een i n terna l , f or g rea ter s ecur ity.

There may h e

s o me r e levance i n t he f act t hat , d isregard ing o r ien ta t ion , many e xamp les a re s i tua ted t o t he n orth o f t he p r inc ip ia , af act wh ich m ight p oss ibly s uggest a t wo s toreyed s tructure p laced i n ap os it ion where i t was l east l ikely t o o bscure t he l i gh t t o t he

p r inc ipa l a dm in istrat ive o f f ices.

I n t he a bsence o f a ny c on-

c lus ive e v idence t o t he c on trary , f or t he p urposes o f t h is s tudy , i th as b een a ssu med t hat t he m il itary h orrea were s ing le s torey s tructures. T here i s n o e v idence a t a l l t o i nd icate t he i n terna l l ayout o f t he g ranary . I n d ea l ing w ith b u lk g ra in t hree methods o f s torage a re p oss ib le;

e i ther

h eaped d irect ly o n to t he f loor , c on f ined i n b ins o r s tacked i n b ags o r s acks. Prev ious ly a l l t he c a lcu la t ions wh ich h ave b een made t o a ssess t he c apac ity o f Ro man g ranar ies h ave a ssu med t hat t he g ra in was s tored i n t imber b ins p laced o n e i ther s ide o f ac en tra l c orr idor.

Haver u ield a nd Col l ingwood e n-

v isaged b ins 1 .83 m ( 6 f t ) d eep w ith a c orr idor 0 .90 m ( 3 f t ) b etween t he m, c over ing t he e n t ire f loor s pace a va ilab le. 3 7

Professor R ich mond , i n h is

s uggested r econstruct ion o f t he t imber g ranar ies a t Fendoch p ostu la ted b ins 1 .50 m ( 5 f t ) d eep. 3 8 I n h is r eappra isa l o f r at ion s torage Mr . Bu l mer b el i eves t ha t a0 .90 m w ide c orr idor i s i nsuf f ic ien t , a nd t ha t b ins 1 .50 m d eep may h ave b een u sed w ith a s lop ing b ase 3 0 cm o f f t he g round a t o ne e nd t o e nab le t he b in t o emp ty c o mp lete ly .

The l oss i n t he amoun t o f s torage a rea

b y t he u se o f t he s lop ing b ase b in w ou ld amoun t t o 3 0% , wh ich h e e l im inates b y r a is ing t he b ack o f t he b in t o 1 .98 m ( 6 f t 6i n ).

I f t h is were d one i t wou ld

l im it t he amount o f wa l l wh ich c ou ld b e p ierced w ith l ouvred v en t i la tors, f or t hey wou ld h ave t o b e b u i lt a t ah igher l evel t han t he t op o f t he g ra in . T he wa l ls o f t imber b ins w ou ld h ave t o w ithstand t he s a me l a tera l t hrus t a s t he e x terna l wa l ls a nd t herefore t hey must h ave b een k eyed i n to t he f loors a nd wa l ls i n s o me way t o p reven t t he m f ro m s l ipp ing f orward u nder t he we igh t o f t he g ra in. A l though i ti s t rue t ha t t he t imber f l oors wh ich may h ave p rov ided t h is e v idence h ave l ong s ince p er ished , h ad t imber b ins b een c ons tructed u pon s tone f l agged f l oors, s uch a s a t C orbr idge , o ne wou ld e xpec t t o f ind t he s ockets o r t imber s lots i n to wh ich t he b ins h ad l ocated ;

f eatures

wh ich h ave n o t y et b een r ecorded . I ti s f eas ible t hat b u lk g ra in c ou ld h ave b een s tored l oose o n t he f loor. Th is method w ou ld h ave b een e x tre mely i nconven ien t.

I t would h ave b een

d if f icu lt t o s epara te f resh g ra in f ro m o ld s tock , a nd r otat ion wou ld h ave b een impeded. Hand l ing wou ld a lso h ave b een h a mpered b ecause t he l oose g ra in wou ld b ehave a s al i qu id a nd b e v ery d i f f icu lt t o c on ta in s uccess fu l ly. The most p ract ica l a nd c onven ien t method o f s tor ing a nd h and l ing wou ld s ee m t o b e t he u se o f c on ta iners , e i ther s acks o r w icker b aske ts , a lthough t he s ack wou ld b e p referab le. T he who le i dea o f t he p rov is ion o f al oad ing p la tfor m s uggests t hat t he g ra in was e nter ing t he g ranary i n s o me f or m o f c onta iner a nd was n ot b e ing s hovel led l oose f ro m t he c ar t o n to t he l oad ing p lat for m a nd t hen i n to t he i n ter ior. t i on o f s tock e as ier.

Th is method wou ld a lso make t he r ota-

I n t he c ase o f s tore d epots , s uch a s S ou th S h ields,

wh ich mus t h ave h ad a f requen t t urnover o f s tock , i ti s d i ff icu lt t o imag ine a ny o ther s yste m o f s torage b e ing p ract icable. Bul mer d is m isses t he i dea o f l ad l ing c orn f ro m t he t op o f t he b in t o e ach i nd iv idua l s old ier q ueu ing u p f or h is g ra in r a t ion b ecause o f t he i neff iciency 1 8

a nd c haos wh ich t h is w ou ld c ause.

As a n a lterna t ive h e s uggests t he u se o f

ab in w ith d ischarge c hute a nd s hut ter.

3 9

But t he n o t ion o f 5 00 o r 1 000 men

q ueue ing u p d a ily t o r ece ive t he ir g ra in r a t ion s ee ms u nrea l ist ic a nd t i me c onsu m ing.

S ure ly i tw ou ld h ave b een more c onven ien t f or a measured q uan t ity

a ppropr iate p erhaps t o ac entury , o r sma l ler u n it t o b e c o l lected b y o ne o r t wo men e i ther d a ily o r w eek ly , t o b e d istr ibu ted amongst t he r e ma inder u pon t he ir r eturn t o t he b arrack a rea. The s tandard modern s ack w e ighs 6 3.5 k g , a nd i s t he c onven ien t l i f t ing a nd h and l ing s ize f or o ne man .

I f w e a ssu me t ha t e ach man was s upp l ied w ith 1 k g

o f g ra in p er d ay ( see b e low , p age 2 5), a c en tury c ons ist ing o f b etween 8 0 a nd 1 00 men wou ld r equ ire 8 0-100 k g.

Two s acks w ou ld e as ily s uff ice f or t he d a ily

n eeds o f a who le c en tury , a nd t h is method o f d is tr ibut ion s ee ms more p robab le. With in p er manen t f or ts e ach c entury a ppears t o h ave b een r espons ib le f or g r ind ing i t s own g ra in , a nd p ossessed i t s own m il l a nd b ak ing o vens. 40

M il l-

s tones b ear ing c entur ia l i nscr ip t ions h ave b een r ecovered f ro m We isbaden b ear ing t he words :

C (entur ia ) C (a i ) Ruf i ;

a nd t wo s uch s tones f ro m Ma inz

b ear t he i nscr ip t ions C (en tur ia ) V ire i a nd C (en tur ia ) V et .4 1 Exa m inat ion o f s im ilar s tones f ro m t he S aa lburg h as l ed J acob i t o r econst ruct t he m il l f ro m wh ich t hey w ere d er ived a s a' s lave ' m i ll i n w h ich a l arge h and le o n ah or izon ta l a x is was t urned t o d r ive g eared s tones o n av er t ica l a x is a t ah igher s peed , c orrespond ing i n i t s ma jor e le men ts t o t he c lass ic V it n iv ian water m i l l.

H e c a lcu la ted t ha t b e tween f our a nd s ix men c ou ld g r ind

1 00 k g o f g ra in ,the amoun t n eeded d a ily b y ac en tury , i n o ne h our .4 2

Mor i tz ,

o n t he o ther h and , s ugges ts a n a l terna t ive r econs truc t ion i n wh ich a n a n i ma l c an d r ive a v er t ica l s ha ft c onnected a t ah igher l eve l t o t he g eared m ill. I n a dd it ion , s evera l much sma l ler s tones h ave b een n oted b y J acobi, b oth f ro m t he S aa lburg a nd f ro m s everal o ther s i tes, i nclud ing N ewstead . e xa mp le f ro m t he S aa lburg b ears t he i nscr ip t ion :

One s uch

Con (tubern iu m ) Br itton is.

I t i s c lear t herefore t ha t s uch s tones were i ssued t o t he c on tubern iu m c ons is ti ng o f 8 -10 men.

T he u se o f t hese p or tab le h and q uerns may h ave b een c on-

f ined t o t he a rmy o n t he march r a ther t han i n p ermanen t g arr ison , a l though t here s ee ms n o r eason why sma l ler g roups s hou ld n ot h ave g round a dd it iona l s upp l ies. The p rov is ion o f b akehouses a nd o vens i n Ro man f or ts i n Br ita in i s , a s y et , p oor ly k nown.

However , e v idence f ro m t he e x tens ively e xcavated Agr ico lan

f or t a t F endoch may s hed s o me l igh t u pon c ook ing a rrange men ts.

F ive o vens

c ons ist ing o f p la tfor ms o f f l at s tones e ach c overed b y ad o me o f r ough s tones mul led w ith c lay w ere l ocated i n t he b ack o f t he r a mpar t o ppos ite t he e nd o f e ach b arrack b lock , s uggest ing t ha t e ach o ven s erved o ne c entury .

The e x-

c avator s upposed t hat e ach c ontubern iu m t ook i t s t urn o n ar ota t o c ook t he d a ily r at ions 3 .

4

Excava t ions o f o ther f or ts s uch a s P en L lystyn a nd B irrens s uggest a lso t he p resence o f l arge w el l b u i lt ' o f f ic ia l ' o vens p robab ly s erv ing a c en tur ia l u n it , w ith f ur ther more h aphazard sma l l o vens s i tua ted a t t he b ase o f t he r a mpar t n earer t he b arrack q uar ters p erhaps t o c a ter f or i nd iv idua ls o r sma l l g roups . 44

2 0

Thus i t s ee ms p robab le t ha t t he s acks o f g ra in a ppropr ia te p erhaps t o e ach c entury f or a d ay 's r at ion was c o l lected f ro m t he g ranary , g round u pon t he c en tury 's own mil l , b aked , a nd o n ly t hen d istr ibu ted t o t he i nd iv idua l s o ld iers.

2 2

6 .

PROV IS ION ING OF RO MAN FORTS

AND THE CAPACITY OF GRANAR IES

I t h as b een e st i ma ted b y modern wr iters t ha t t he n or ma l r a t ion o f g ra in c onsu med b y o ne man i n ad ay was 3 l b ( 1 .36 k g ).

T ak ing t h is f igure , c al-

c u lat ions h ave b een made t o a ssess t he p oss ib le r equ ire men ts o f ag arr ison a nd t he amoun t o f s torage s pace n ecessary t o h ouse t he m. 45

Two i ndependen t

a ssess men ts h ave b een made o f t h is f igure , t he f irst b ased u pon r esearch i nt o C lass ica l we igh ts a nd measures , a nd t he s econd b y p ract ica l e xper i men t. There i s al i t t le c on temporary e v idence f or r a t ions a nd s upp l ies i n t he Ro man ar m y. Po lyb ius, w r it ing c . 1 40 B .C. d escr ibes t he p ay o f d i f f r anks o f s old iers a nd a lso t he ir month ly c orn a llowance : 46

cn t

Leg ionary : i nfan try s o ld ier r ece ived 2 /3 A t t ic med i mnus

k g

c ava lry s o ld ier r ece ives 7 med i mn i b ar ley

=

2 58.0 k g

=

8 4.8 k g

i nfan try s o ld ier r ece ives 2 /3 A tt ic med i mnus

=

2 8.3 k g

c ava lry s o ld ier r ece ives 1+ 1 /3 med i mn i whea t

=

5 6.5 k g

2 med i mn i wheat Aux il iary :

5 med i mn i b ar ley The a l lowance p er d ay e qua ls : Leg ionary :

Aux il iary :

i nfan try man

=

c ava lryman

=

8 .60 k g ( 18.92 l bs ) o f b ar ley

=

2 .83 k g ( 6 .23 l bs ) o f whea t

i n fan try man

=

0 .94 k g ( 1.88 l b )

c ava lryman

=

1 .88 k g ( 3.76 l bs ) o f whea t

=

6 .14 k g ( 13.50 l bs ) o f b ar ley

0 .94 k g ( 1.88 l b )

The A t t ic med i mnus w as e qu iva len t t o 6 Ro man mod i i o r 2 ar nphorae. 4 ' I n modern

te r

m s

i ti s e qua l t o n ear ly 1 2 g a l lons. 48

mately 2 g a llons ( 15.36 p in ts ).

The mod ius was a pprox i-

Dry measures o f s uch c o m mod it ies a s g ra in

were r eckoned i n p in ts a nd g a l lons.

T he n or ma l d ry measure we igh t a nd

metr ic c apac ity were worked o u t b y o bta in ing 1. 36 k g ( 3 l bs ) measures o f wheat a nd b ar ley . One p in t o f whea t was f ound t o w e igh 0 .46 k g , a nd a g a l lon , 3 .68 k g. med i mnus wou ld c on ta in 4 2.39 k g a nd a mod ius 7 .07 k g.

A

One p in t o f b ar ley

we ighed 0 .40 k g , g iv ing t he we igh ts o f a med i mnus a nd mod ius a s 3 6.86 k g a nd 6 .14 k g r espect ive ly .

I t i s u pon t hese f igures t hat t he a bove s tate men t

o f Po lyb ius h as b een i n terpreted. Ano ther r eference t o t he g ra in r equ ire men ts o f t he Ro man s o ld ier o ccurs o n o s traca f ro m Pse lc is ( modern Dakkeh ). These r ecords i nclude r ece ip ts f or f ood a nd w ine f or a c ohors e qu itata , p robably I I turaeoru m.49

S evera l

r ece ipts r ang ing i n d ate f ro m N ov. 1 79? t o S ep t. 2 05 ( A. D .) r efer t o t he g ra in r at ion o f as o ld ier p er mon th a s o ne a r taba. 2 3

The a r taba w as o r ig ina l ly a P ers ian d ry measure e qua l l ing , a ccord ing t o Herodo tus, 1 A t t ic med i mnus a nd 3 c hoen ices

=

1 2.75 g a l lons a pprox .

e ver , i t was a lso a n Egyp t ian measure c ons ist ing o f a n o ld measure , Ro man mod i i

=

a pprox . 9g a llons ;

t h ird mod i i, o r 6 .5 g a l lons.

5 0

How4 .5

o r an ew a r taba wh ich e qua l led 3 a nd o ne

T he n ew a r taba w as more c o m mon a nd i th as

b een p resu med t hat b y t he e nd o f t he 2 nd c en tury A .D . t h is was t he measure t o wh ich t he r ece ip ts r efer . I fo ne Ro man mod ius c onta ined 1 5.36 p in ts , 3 .33 mod i i

=

5 1.2 p in ts, a nd

a n a r tab wou ld w e igh 2 3.6 k g ( t he mon th ly i nd iv idua l r a t ion ). would b e 0 .80 k g ( 1 .75 i b ).

The d a ily r at ion

The mod ius f ro m Carvoran was f ound t o c on ta in a l most 2 0 p in ts , wh ich wou ld measure a q uan t ity o f a pprox i mately 9 k g o f w hea t.

5 1

Tak ing t he a ver-

a ge d a i ly r a t ion s uggested a bove t h is mod ius c ou ld s upp ly t he n eeds o f t en men . The sma l lest u n it a cco m moda ted w ith in t he m il itary b arracks was a c on tubern iu m o f , t heoret ica l ly , t en men.

However , i ti s t o s tray t oo f ar i n to t he

r eal ms o f s uppos it ion t o l i nk t hese t wo f actors , a nd i ti s more l ike ly t ha t t h is mod ius r epresen ted s o me f or i r i o f s tandard i mper ia l measure wh ich wou ld n o t h ave b een i n d a ily u se f or measur ing o u t r a t ions. T he r eferences wh ich a re a va ilab le d o s ee m t o i nd ica te t hat t he d a ily g ra in r at ion f or t he i n fan try s o ld ier was l ower t han 1. 36 k g a nd w as p robab ly n earer 1k g ( 2 .21 l bs ). I n o rder t o e xa m ine t he a ctua l q uan t ity i nvo lved a 1 .36 k g s a mp le was o bt a ined .

C lear ly i ti s imposs ib le t o a nswer e ven f unda men ta l q uest ions i nvo lv-

i ng t he a ppet ite o f t he Ro man s o ld ier , b ut n ever theless a 1 .36 k g u ncooked we igh t o f c erea l d oes a ppear t o b e more t han a dequa te.

The s a mp le was

mil led i n ar o tary g r inder a nd m ixed w ith w ater t o t est t he b ind ing p roper ty o f t he f lour , b ut t he q uan t ity o f b ran i nh ib ited t he p roduct ion o f ap roper d ough , a nd when b aked a c rude ' cake ' r esu lted . t he o r ig inal s a mp le a nd t he e nd p roduct.

T here w as n o l oss i n we igh t b etween The q ua l ity o f Ro man m i l itary f lour

c anno t b e k nown w ith a ny c er ta in ty , b ut P l iny i n h is N atura l H istory s tates t hat :

" I t i s as ure l aw o f n ature t hat w ith a l l k inds ( o f whea t ) a r my b read i s

h eav ier b y o ne t h ird t han t he g ra in ."

Mor itz p o in ts o ut t ha t t h is k ind o f b read

y ield , when c o mpared w ith modern e qu iva len ts , w ou ld most p robab ly h ave b een d er ived o n ly f ro m who le mea l o r f ro m mea l o f a pprox i ma tely 9 5 t ion.

5 2

e x trac-

Th is e xper i men t d e monstrated t ha t ac ons iderable amoun t o f p repara-

t ion was n ecessary t o p roduce f lour s u itab le f or b read mak ing.

I tw ou ld s ee m

u n l ikely t ha t al arge g roup o f men wou ld e i ther w an t t o , o r b e a l lowed t o , s pend t he amoun t o f t ime n ecessary t o p roduce f l our f or b ak ing d a i ly .

F or , o ne man

p roduc ing a l oaf w ith a n i nd iv idua l q uern wou ld t ake t he s a me t ime a s al arge c o m muna l m i l l p roduc ing b read f l our f or a l arger n u mber . Fro m t hese c ons idera t ions t wo ma in p o in ts emerge. t hat p erhaps t he C lass ica l r eference t o a

d a ily

F irst ly , t he n ot ion

o r mon th ly ' r a t ion i s at oken

r eference t o t he amoun t o f g ra in wh ich s hou ld t heoret ica lly b e a l loca ted p er h ead w ith in t he g arr ison ; whether e ach man a ctua l ly r ece ived h is c o mplete g ra in r a t ion d irect ly f ro m t he g ranary c anno t b e d eterm ined o n t he p resen t e v idence.

Cer ta in e p igraph ic i n for ma t ion d oes e x ist wh ich may h e lp t o c lar ify

t h is p o in t al i t t le.

S evera l o f t he o straca f ro m P selc is r ecord r ece ip ts b y

i nd iv idua ls f or i nd iv idua l mon th ly g ra in r at ions, a no ther e xa mp le i l lustrates

2 4

ar ece ip t f or 5 0 a r tabas w h ich i s s igned b y t he f i f ty men c oncerned.

5 3

But i t

i s n o t a bso lute ly c lear whe ther t hese a re r eferences t o i nd iv idual a l loca t ion a nd r espons ib il ity o r whether i ti s p ar t o f f or ma l Ro man mi l itary p rocedure f or men t o h ave t o s ign r ece ip ts p er iod ica l ly , p erhaps mon th ly , f or mater ia ls r ece ived. The s econd c ons idera t ion i s t ha t t he p reparat ion o f b read f lour i s al eng thy a nd r e la t ively s pec ia l ised p rocess , wh ilst t he p reparat ion o f as i mp le c erea l f ood s uch a s p orr idge i s q u icker a nd i nvo lves much l ess e f fort .

I t i s p oss ib le

t ha t p ar t o f t he r a t ion w as a l located t o t he men f ro m t he g ranary f or t h is p urp ose w h ilst t he r est wou ld b e a l lo ted t o t he b akery , c ook ing b read f or l arger u n its. T h is wou ld e l im ina te t he n eed f or l arge n u mbers o f i nd iv idua l a nd o vens.

e rns

T ak ing t he e s t i mate o f 1k g o f g ra in a s e ach man 's d a ily c onsu mpuon

i '

i s

p oss ib le t o c a lcu late, v ery a pprox i mate ly , t he p oss ib le r equ ire men ts o f a g arr ison , a nd t o s ee wha t r e lat ionsh ip t h is b ears t o t he s torage a rea a va ilab le w ith in t he g ranary.

One man w ou ld r equ ire 3 65 k g a nnua l ly , a nd a g arr ison

o f 5 00 men , 1 82,500 k g a nnua l ly .

Ca lcu lat ions may a lso b e a tte mp ted t o

e st i mate t he amoun t o f s torage s pace n eeded f or s uch q uan t it ies. a nd v o lu mes o f v ar ious c erea ls h ave b een t abu lated b elow :5 4

Co m mod ity Whea t

k g/m e

m 3/ tonne

7 85

1 .3

Bar ley

7 05

1 .4

Oa ts

5 13

1 .9

Rye

7 05

1 .4

Ma ize

7 53

1 .3

T hus 7 85 k g o f whea t o ccupy 1 c ub ic metre o f s torage s pace. n eeded t o h ouse t he g ra in r at ion o f 5 00 men wou ld b e : c ub ic metres , i ft he g ra in was s tored i n b u lk . t he v o lu me r equ ired wou ld b e i ncreased b y

The \e igh ts

1 5% ,

The s pace

1 82 5 00/785 =232.5

I ft he g ra in was s tored i n s acks , t o g ive t he t ota l s torage r e-

q u ired f or t he r a t ions o f 5 00 men a s 2 67.4 c ub ic metres.

5 5

Theoret ica l ly i t s hou ld b e r easonab ly s tra ightforward t o c o mpare t hese f igures w ith t he f l oor a reas p rov ided b y h orrea i n Ro man f or ts a nd t o e s t i ma te t he s ize o f t he g ra in s upp ly i n s torage a nd t he l eng th o f t ime f or wh ich i tc ould s upp ly a g arr ison o f ac er ta in s ize.

T ak ing a s t he b as is f or t he ir s tudy t he

s tate men t o f Tac itus t ha t Agr ico la s ecured h is f or ts f ro m p ro trac ted s e ige w ith s upp l ies s uff ic ien t t o l ast a y ear , a nnu is c op i is , Haver f ie ld a nd Co ll ingwood a tte mp ted t o e st i mate t he c apac ity o f e ach o f t h ir teen g ranar ies b y a ssu m ing t ha t t he g ra in was s tored t o ah e ight o f 1 .83 m, i n b ins 1 .83-2.44 m w ide, w ith a 0 .90 m c orr idor .

T he ir c a lcu lat ions a ssured t he m t ha t t he e xa mp les

s tud ied w ere a b le t o s tore t w ice t he q uan t ity o f g ra in r equ ired i n ay ear.

5 6

S im i lar c a lcu la t ions may b e a tte mpted f or t hree e xa mp les : 1 .

G el l igaer

-

t wo g ranar ies , e ach 1 6.15 x 7 .01 m i n terna l ly .

I f a1 .50 m

c orr idor i s l ef t d own t he c en tre o f e ach g ranary , t he s torage s pace i n e ach wou ld b e 2 .75 x 1 6.15 x 2 m 2 . I ft he g ra in was s tacked 2 .5 m h igh i n o ne

2 5

g ranary t he s pace o ccup ied wou ld b e 2 22 m , r equ ir ing t he o ther 4 5 m

t o b e

a cco m moda ted i n t he o ther g ranary i n o rder t o f eed t he s upposed g arr ison , a c ohors q u ingenar ia p ed ita ta , f or a y ear. 2 .

Housesteads

l y .

-

t wo s ides o f ad oub le g ranary b o th 2 3.78 x 5 .49 m i nterna l-

A l low ing a 1 .50 m c orr idor , s torage s pace o n o ne s ide wou ld b e 2x 2x

2 3 7 8 m2. I ft he g ra in was s tacked 2 5 m h igh i n o ne g ranary i tw ou ld p rov ide .

.

s torage s pace f or 2 37.8 m .

The g arr ison o f t he f or t i s t hough t t o h ave b een

ac ohors mil l iar ia p ed itata , a nd b oth g ranar ies w ou ld h ave h ad t o h ave b een s tacked w ith s acks t o ah e igh t o f 2 .8 m t o s upp ly s uch a g arr ison f or a y ear . 3 .

Caerhun

-

t wo s ides o f ad oub le g ranary , b o th 2 0.57 x 6 .86 m i n terna l i.

A l low ing a 1 .50 m c orr idor , t he s torage a rea o n o ne s ide wou ld b e 2x 2 .6 2 0 5 7 m2. I ft he g ra in was s tacked 2 5 m h igh i n o ne s ide i t wou ld p rov ide .

.

s torage f or 2 75.6 m , s uf f ic ien t t o s upp ly t he s upposed g arr ison , ac ohors q u ingenar ia e qu itata f or a y ear , l eav ing t he o ther s ide emp ty.

I t must b e

r e me mbered , h owever , t ha t n o p rov is ion f or h orse f odder h as b een made. However , t here a re t oo many u nknown f actors t o make t h is k ind o f c a lcu lat ion r ea l ly mean ing fu l.

Un less t he f or t h as b een t o ta lly e xcavated i ti s n ot

p oss ib le t o k now whether t he f u l l c o mp le men t o f g ranar ies h as b een d iscovered. There may h ave b een g ranar ies a dd it iona l t o t hose i n t he c en tra l r ange s i tuat ed i n o ther p ar ts o f t he f or t , a s i l lustra ted a t Dru mburgh ( Fig. 1 0 ), Chesterl e-S treet , o r B irrens.

Withou t k now ing e xact ly h ow many men t he g ranar ies

h ad t o s upp ly o r t he n u mber o f a n i ma ls t o b e ma in ta ined , a nd i n t he a bsence o f a ccurate k now ledge a s t o t he d a ily g ra in a l loca t ion i ti s i mposs ib le t o make f in ite s tate ments c oncern ing g ra in r eserves a nd c apac it ies.

I t i s n o t p oss ib le

t o k now t he q uan t it ies o f o ther f oodstuf fs s tored , n or o f t he p ropor t ion o f t he Ro man mi l itary d iet wh ich t he g ra in r a t ion r epresen ted. The ma in emphas is i s t hough t t o h ave b een o n t he s torage o f c erea ls , b u t many o ther f oods must h ave b een s tored i n t he g ranary ;

t he l ow t e mperature

a nd a dequa te v en t ilat ion wou ld h ave s erved a s al arge-sca le r efr igera tor t o p reserve a l arge v ar iety o f f oodstuf fs , a nd t he s o l id ity o f t he c onstruct ion wou ld h ave p rov ided g reater s ecur ity f or t he e n t ire g arr ison 's p rov is ions. These must h ave i nc luded b acon , c heese, l ard , o l ive o il , v egetab les , s our w ine a nd mea t. 5 7 There may e ven h ave b een s ome p rov is ion f or t he h ang ing o f c arcasses f ro m t he r a f ters i n much t he s a me manner a s a modern c o ld s tore.

S evera l C lass ica l a u thors , a nd a p a in t ing f ro m Po mpe ii, d escr ibe

t he u se o f t he c arnar iu m , af ra me s uspended f rom t he c e il ing c o mpr is ing as er ies o f h ooks u pon wh ich p rov is ions were h ung , u sed i n t he k i tchen a nd t he t avern.

I t i s e qua l ly p oss ible t hat s uch d ev ices may h ave b een u sed i n

mil itary h orrea.

Desp ite t he l ack o f c onte mporary r eferences t he l arge

5 8

n u mber o f a n i ma l

b ones f ro m Ro man m il itary s i tes r evea l t hat a g reat d ea l

o f mea t was e a ten .

5 9

Vegetab le r e ma ins h ave b een r ecorded a t Caer Sws

a nd c abbage i den t if ied f ro m Chesterho im ;

a n o s traca f ro m Pselc is a lso

r ecords a r ece ip t f or l en t ils , s a lt a nd v inegar.

W ine wou ld p robab ly h ave

a lso b een s tored w ith in t he g ranary , a nd s evera l h ave r evea led amphora f rag ments d ur ing e xcavat ion , s uch a s Ba l mu ildy a nd I lk ley . The ma in emphas is was o n c erea ls , h owever , a nd many e xa mp les o f c harred whea t h ave b een f ound i n g ranar ies d ur ing e xcava t ions ;

2 6

al arge

q uan t ity o f c harred wheat was d iscovered a t R ibchester a nd sma l ler q uan t it ies f ro m Ambles ide , B irrens , Castel l Co h en , Grea t Chesters , Ha ltonchesters a nd I lk ley , wh ilst c arbon ised whea t a nd b ar ley c a me f ro m Brough b y Ba inb r idge.

The q uan t it ies r ecovered h ave b een t oo sma l l t o g ive a n o vera l l p ic-

t ure o f t he c erea ls p referred b y t he a r my , b u t f ro m h is e xa m inat ion o f c arboni sed g ra in f ro m a l a te 1 st-ear ly 2 nd c en tury h ut a t Caer leon , Dr . He lbaek h as b een a ble t o i den t ify s pe l t , b ar ley a nd p oss ib ly r ye. 60 T here a re s evera l o ther f actors wh ich must b e t aken i n to c ons idera t ion. Desp i te t he s tate men t o f T ac itus ( see p age 2 5), i ti s n o t k nown f or h ow l ong t he s upp l ies w ere s upposed t o l ast ;

t here may h ave b een i nstances where i t

was a bso lutely n ecessary f or a f or t t o h ave a y ear 's s upp ly i n r eserve , wherea s i n o thers i ti s q u ite f eas ible t ha t o n ly a f ew mon ths ' o r weeks ' s upp ly may h ave b een n eeded , d ependen t u pon t he r e lat ive s ecur ity a nd s trateg ic p os it ion o f t he f or t.

I t i s c lear t ha t S ou th S h ie lds was a s upp ly d epo t f or S everan a c-

t iv it ies f ur ther n or th , b ut t here may we l l h ave b een o ther f or ts wh ich a lso h e ld r eserve s upp l ies t o p ass o n t o f ron t ier p osts a s t he n eed a rose, s o t hat a s ystem may h ave a cted a s ac ha in o f s upp ly , p erhaps w ith r eserves a t s trateg ic p o in ts ( F ig. 4 ).

I t may h ave b eco me n ecessary t o r e inforce c erta in a reas t hus

p lac ing i ncreased d e mand o n t he s upp l ies o f t he l oca l ity.

I n t h is s or t o f s i tua-

t ion i ts ee ms i mpract ica l t o imag ine t he u n it n eed ing t o wa it f or a nd d epend u pon s upp l ies f ro m a d istan t d epot.

I t s ee ms more f eas ib le t ha t ar ec iproca l

o pera t ion wou ld b e i n f orce , whereby r eserve s tores o f g ra in c ou ld b e p assed ; o n f rom h o ld ing d epots , w h ich t he mse lves c ou ld b e r ep len ished s ubsequen t ly more r ead ily f ro m a ma in s upp ly b ase. P erhaps a more v a l id w ay o f a ssess ing g ranary c apac it ies i n r elat ion t o p oss ib le g arr ison a nd f ort s ize , i n t he a bsence o f a ny e p igraph ic a id , i s t o e qua te t he amoun t o f s pace d evoted i n t he f or t t o g ranar ies, r elat ive t o t he t ota l f or t a rea. Even t hen i ti s n ot p oss ib le t o s ay e xact ly wha t f unct ion t he f or t p er formed , o r h ow many men were i n p ermanen t g arr ison.

I t must b e

n ecessary t o f a l l b ack o n t he a ssu mpt ion t ha t i f al arge e nough c ross s ect ion i s e xam ined s ome k ind o f p roport iona l p at tern may emerge , a nd a no ma l ies may b eco me a pparen t.

C o mpar ison h as b een made b etween t he amoun t o f

g ranary f loor s torage s pace a va ilab le a nd t he i n terna l a rea o f t he f or t wh ich i ts erved.

I n T ab le I t he b as ic i n forma t ion i s p rov ided , a nd t he i n terna l

a nd e x ternal f or t a rea ( i n h ectares a nd s quare metres ), a nd t he g ranary f loor a rea a va ilable a re e xpressed p ropor t iona l ly . t erns w h ich emerged h ave b een c o mpared.

I n F ig . 5t he p ropor t iona l p a t-

I n i nstances where t here i s s o me

e v idence t o s uggest t he p resence o f as econd g ranary , a l though i th as n ot b een f u l ly e xcava ted , t he f l oor a rea h as b een a ssu med t o e qua l t ha t o f t he e xt an t e xamp le, a nd t he p oss ib le a dd it iona l a rea h as b een s t ipp led.

A s econd

g ranary h as o n ly b een s uggested where t here i s s o me f irm e v idence f ro m t he e xcava tor f or i t s e x istence a s a t Cast lecary , o r a t B irdoswa ld , where t wo g ranar ies h ave b een d etected b y a er ia l p hotography. 6 1 I t c an b e s een t hat t here i s , b road ly s peak ing , ar elat ive ly c onstan t r e lat ionsh ip b etween f or t s ize a nd t he a rea d evoted t o g ranar ies , whe ther i n t he l eg ionary b ase a t Chester o r t he f or t a t Housesteads. I ti s r easonab le t o a ss u me t hat t h is i s ar e la t ionsh ip i n t erms o f t he n u mber o f men a cco m modated i n t he f or t , l eav ing a s ide t he p rob le ms c aused b y t he a dd it iona l r equ ire men ts o f c ava lry d etach men ts.

S evera l a no ma l ies a ppear , n otab ly Benwel l, B irrens ,

2 7

Ha ltwh iSt le Burn , Lyne a nd S outh S h ie lds ( Severan ).

The l a tter a ppears t o h ave

b een a b ase u sed t o s upp ly t he S everan S cot t ish c a mpa igns.

I t h as b een s ug-

g ested t hat Benwe ll h eld a dd it iona l s upp l ies i n r eserve f or o ther f or ts a long t he Wa l l l ine a s i t was t he f ur thest p o in t u p t he T yne wh ich was n av igab le 6 2 Ha ltwh ist le Burn f or t let s ee ms t o h ave a g ranary f ar i n e xcess o f t he n eeds o f t he sma l l g arr ison wh ich c ou ld h ave b een c a tered f or , a nd may h ave f unct ioned a s ar eserve.

I t i s p oss ible t hat Dru mburgh , w ith o ne g ranary b u ilt s o

c lose t o t he n or th-west a ng le, may h ave p ossessed more , a nd may h ave h e ld r eserve p rov is ions t o s upp ly f or ts a long t he Wa l l f ro m t he w est , r ep len ished b y s ea f ro m f ur ther s ou th.

Perhaps when f ur ther e xcava t ion h as b een c arr ied

o ut a c learer p ic ture o f t he s upp ly a nd d istr ibut ion o f t he g ra in a nd s upp l ies may emerge. Tab le 2 s ets o u t t he t heoret ica l a nnua l g ra in r equ ire men t , i n c ub ic metres , o f t he f or ts l i sted i n t he c ata logue b ased u pon t he ir p resu med g arr isons.

F or

t hese p urposes , i th as b een a ssu med t ha t t he g ra in i s s tored t o ah e igh t o f 2m ( see p age 2 5 ).

An a dd it iona l t ab le h as b een a dded ( Tab le 3 ) t o s how t he

r elat ionsh ip w ith s ix o f t he more f u l ly e xcavated t imber e xamp les.

A lthough

t he t ab les a re b ased e ssen t ia l ly u pon c on jecture s o me i n terest ing r esu lts c an b e s een .

F or e xa mp le, t he f u l ly e xcava ted f or t o f Housesteads h as r evea led

t en b arrack b locks , e ach w ith 1 0-11 c on tubern ia , imp ly ing a g arr ison o f a c ohors mi l l iar ia p ed itata.

I ts t heoret ical a nnua l g ra in r equ ire men t , b ased o n

p rev ious c a lcu la t ions ( see p age 2 5 ), w ou ld b e 5 35 m 3 ; t he c apac ity o f t he g ranary i f s tacked t o ah e igh t o f 2 metres wou ld b e 5 22 m 3. Th is n eed n ot , o f c ourse , imp ly t hat t he f ormu la c an b e e x tended t o o ther f or ts a nd i ndeed i t c an b e s een t ha t many wou ld , u s ing t h is f ormu la , p ossess g ranary s torage c apac it ies r ough ly t w ice t he t heoret ica l a nnua l r equ ire men t n ecessary f or t he ir p resu med g arr isons.

However , i n many c ases i t must b e r e me mbered

t hat t he g arr isons h ave o n ly b een s uggested f ro m i n terpreta t ion b ased u pon p ar t ia l e xcavat ion o f t he f or t 's i n ter ior. The most a pparen t d iscrepancy i s a ssoc iated w ith g ranar ies i n f or ts wh ich a re

p resu med t o h ave h oused c ohors q u ingenar ia , e i ther p ed itata o r e qu itata ,

e .g. Amb les ide, Ba l mu ildy , Ha ltonchesters e tc., wh ich a ppear t o h ave a g ranary c apac ity o f r ough ly t w ice t he ir t heoret ica l a nnua l r equ ire men t.

On

t he o ther h and t hose f or ts t hough t t o h ouse c ohors mil l iar ia , b road ly s peaki ng , c orrespond.

These i ncons istenc ies may b e s een a s ar ef lect ion o f o ur

l ack o f k now ledge o f t he i n terna l l ayou t o f t he f or t , d iff icu l t ies i n t he i dent ifi cat ion o f s tab l ing , t he a ssu mpt ion o f a sma l ler g arr ison t han was a ctua lly p resen t , t he h old ing o f g ra in s upp l ies i n e xcess o f T ac itus ' a nnu is c op i is , o r f ina l ly , t hat c er ta in f or ts h e ld g ra in r eserves t o p ass o n t o o ther g arr isons. The i ssue i s c o mp lex , b u t f ro m t hese r esu lts i ti s c lear t hat t he s tudy o f mil itary g ranar ies d oes h ave a n impor tan t c on tr ibu t ion t o make i n a ny c ons iderat ion o f t he g arr ison ing o f Ro man f or ts.

2 8

TABLE 1 GRANARY FLOOR AREA EXPRESSED AS A PROPOR T ION OF THE TOTAL I NTERNAL FORT AREA

Area ( ha ) Overa l l

For t Amb les ide

I n terna l

s q m

Granary f l oor

Propor-

a rea ( sq m)

t i on

1 .22

1 .04

1 0 ,400

2 28.6

2 .2

Ba l mu i ldy

1 .76

1 .32

1 3,200

2 71.7

2 .1

Bar H il l

1 .37

1 .29

1 2,900

2 10.5

1 .6

Benwe l l

? 2.24

? 1.84

? 1 8,400

? 613.7

? 3.3

B irrens

1 .97

1 .65

1 6 ,500

4 75.8

2 .9

Brecon Gaer

3 .14

2 .57

2 5,700

2 70.0

1 .1

Cadder

1 .34

1 .15

1 1,500

1 59.3

1 .4

Caerhun

1 .97

1 .60

1 6,000

2 82.2

1 .8

Caernar fon

2 .27

1 .97

1 9,700

3 17.6

1 .6

Caersws l

3 .11

2 .50

2 5 ,000

1 70.9

0 .7

Ca melon

3 .69

2 .41

2 4,100

1 30.2(240.8 )

0 .5 (1.5 )

Cappuck

0 .60

0 .50

5 ,000

4 6.9

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Castei l Co l len

1 .77

1 .46

1 4,600

1 79.5

Cast lecary

1 .58

1 .48

1 4 ,800

1 15.6 (115.6 )

Cast ledykes

3 .69

2 .46

2 4,600

3 03.9

Ches ter

2 4.33

2 3.42

2 34 ,200

1 591.3

1 .2 0 .8 (1.6 ) 1 .2 0 .7 (1.4 )

( 159t.3 ) Chesters

2 .35

1 .96

1 9,600

1 72.0

Craw ford 1

0 .79

0 .61

6 ,100

9 5.5

0 .9 1 .6

Croy H ill

0 .80

0 .62

6 ,200

4 5.8

0 .7

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1 .49

1 .15

1 1,500

2 26.4

2 .0

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1 .75

1 .48

1 4 ,800

? 330.0

2 .2

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0 .32

0 .28

2 ,800

8 5.2

3 .0

Hardknot t

1 .31

1 .07

1 0.700

1 35.4

1 .3

H igh Rochester

2 .01

1 .70

1 7,000

3 59.2

2 .1

Housesteads

2 .10

1 .73

1 7,300

2 61.1

1 .5

I lk ley

0 .97

0 .70

7 ,000

1 52.8

2 .2

Lyne

2 .61

2 .24

2 2,400

8 61,0

3 .8

Mu mr il ls

2 .86

2 .64

2 6 ,400

2 36.8

0 .9

Newstead

6 .20

5 .40

5 4,000

7 53.8

1 .4

O ld Church

1 .52

1 .27

1 2,700

2 73.3

2 .2 0 .8 (1.7 )

O ld K ilpa tr ick

1 .91

1 .68

1 6,800

1 32.2 (158.0 )

R ibches ter

2 .50

2 .00

2 0 ,000

3 14.2

1 .6

Rough Cas t le

0 .66

0 .42

4 ,200

9 7.1

2 .3

Rudchester

1 .85

1 .51

1 5,100

2 46.8

1 .6

S lack

1 .50

? 1.30

? 1 3,000

1 91.7

1 .5

S outh S h ie lds ( Had.) 2 .09

1 .73

1 7,300

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2 61.4

1 .5

2 506.5

1 4.5

3 .77

3 .65

3 6,500

2 54.4 (254.4 )

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1 .37

1 3,700

3 18.9

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APPEND IX I

CALCULAT ION TO ASSESS THE CAPAB IL ITY OF THE WALLS OF THE CORBR IDGE WEST GRANARY ( PHASE 4 ) TO WITHSTAND THE LATERAL THRUST EXERTED BY THE GRA IN I N STORAGE

Let w a l l t h ickness

=

t

Let h e ight o f g ra in s tacked a ga inst wal l Le t l a tera l t hrus t o f l eve l g ra in Let t he mass o f t he wa l l M

=

gV

=

=

=

h

T

M

Where p is t he d ens ity o f t he wa l l ma ter ia l , V i s t he v o lu me a nd gi s t he a cce lerat ion d ue t o g rav ity.

M

p whtg p er metre w idth.

Assum ing t ha t t he g ra in i s s tored i n ab in whose l eng th a nd b read th a re e qua l t o t he h e ight , T=

-

h2 h gx-- x- g

t he max i mu m p ressure i s a ssu med t o b e a t o ne t h ird o f t he way u p t he wa l l.

For e qu il ibr iu m , a nd t ak ing mo men ts a bout 0 : t

pwght x =p g

pwt

= f ig

t=

h h — x- g

1

/

' I 3p

Assu m ing pw

=

2 200 k g/ m a 6 3

p g= 7 85 k g/ m e

Tak ing t he h e igh t , ha s 3 m, / 785 x3 3x2200

m

=0.60 m

Tak ing t he h e igh t a s 2 .5 m,

t =

7 85 x 2 .5 3x2 200

m

=

0 .55 m 3 5

6 4

Similarly, the width of the wall needed to withstand grain stacked to a height of 2 m is 0.49 m, and to a height of 1.5 m is 0 ..42 m. Thus the 1.06 m thick­ ness of the Corbridge walls would be more than sufficient to withstand the pressures of grain stacked against them to a height in excess of 3 m.

36

APPENDIX 2 AN ATTEMPT TO ASSESS THE WEIGHT OF THE ROOF OF THE WEST GRANARY (PHASE 4) AT CORBRIDGE Five tegulae and six imbrices from Caerleon, in the collection of the National Museum of Wales, were weighed and measured in an attempt to es­ timate the average weight of a granary roof. The average size of a tegula was found to be 55 cm long, including a 5 cm overlap; and 38 cm wide, with an average weight of 25 lbs (11.34 kg). Imbrices with the same length weighed approximately 8 lbs (3.63 kg). Taking Corbridge as an example, the length of the building is approximately 30 m and the width 9 m. The pitch of the roof is dependent upon the roof cover­ ing. In the case of tiles the pitch must be steep enough to allow rainwater to drain successfully and 25 degrees would seem sufficient. If such a pitch is allowed, it is calculated that the length of the rafters needed would be 6 m, in­ cluding an overhang which continues to the outer face of the buttresses. Each half of the roof woulcj. need: 80 tegulae to cover the 30 m length 12 tegulae to cover the 6 m rafters = 960 tegulae In addition, a similar number of semi-circular imbrices would be necessary to cover the junctions of the tegulae = 960 imbrices. The total number of tiles for the entire roof = 1920 tegulae The approx. weight of 1920 tegulae

= =

The approx. weight of 1920 imbrices Total weight of tiles estimated:

+

1920 imbrices.

1920 x 25 lbs (11.34 kg) 48 000 lbs (21 772 kg)

1920 x 8 lbs (3.63 kg) = 15 360 lbs (6 969 kg) =

= 63 360 lbs (28 740 kg) = 28 tons

Although the method of roof construction of such a building is completely unknown, it is reasonable to suppose that it was similar in many respects to the simple Medieval examples, in which the tiles would have been supported by a framework of timber trusses. These timbers would take the form of a triangular frame consisting of two rafters meeting at the ridge and held rigid by means of a horizontal tie beam, and keyed into the top of the wall by longitudinal wall plates. They would have been placed at regular intervals along the length of the building, the tie beams probably supported, as in the Corbridge example, upon paired buttresses. Other longitudinal timbers would have been added to give the framework rigidity, purlins half way up the roof on each side, and a ridge piece at the apex of the rafters. Laths 37

may have been added to give further strength, and to support the tiles. Fig. 1).

(See

The tapering of the regulae exerts a latera:l thrust which helps to lock the body of tiles together, on a relatively shallow pitched roof. A·lso, the notch­ ing of the tegulae and the nail holes present in the imbrices examined suggest that they could have been secured adequately as in Fig. 2, without mortaring, although the joints between the tiles were probably mortared to render them watertight. Thus, in addition to the weight of the tiles, the weight of the timber roof frame must also be taken into consideration. This calculation assumes that a 30 m length of oak 9 x 6 in (229 x 152 mm) weighs 1653 lbs (750 kg). 5 x 30 m lengths would probably be needed; 2 for the wall plates, 2 for the purlins, and 1 ridge piece. Their combined weight would be: 5 x 1653 lbs= 8265 lbs (3 750 kg) 10 tie beams would be needed, 1 upon each end wall, and etght supported by = 10 x 551 lbs (250 kg) the eight intermediate buttresses, = 5510 lbs (2500 kg)

Also, 10 x 12 m lengths for the rafters= 10 x 660 lbs (300 kg). = 6600 lbs (3000 kg) Allowing an extra 4 x 30 m lengths for laths = 6600 lbs (3000 kg) Total estimated weight of timbering = 26 975 lbs (12 250 kg) = 12 tQns These calculations would give the very minimum estimated weight of the roof of one of the Corbridge granaries including both tiles and timbers as 40 tons.

38

APPENDIX 3 TO DETERMINE THE SIZE OF BUTTRESSES NECESSARY TO SUPPORT A TILED ROOF OF .JcO TONS WEIGIIT (Taking the west granary at Corbridge (Phase 1), as an example)

T otal weight of roof= -±0 tons = -±0 6-±1. 88 kg. Assume this to be equally carried by 8 roof trusses supported on pairs of buttresses. W=

40642 8

cc

5080 kg

each reaction W = 2540 kg 2 If each support were placed vertically (without side support to pre\'ent bending) Euler's theory of struts could be applied:

w

Where E = Young' s Elastic Modulus I= Moment of inertia of support

3

Ixx=

l )